Round Duct Connections
METU-SYSTEM Catalog 6b
20
Overview
22
Circular Flanges AF
26
Circular Flanges UF
29
Circular Flanges BF
33
Circular Flanges LF
37
Circular Flanges MF
40
Joining Clips SR
44
Round Flexible Connectors RFS
47
Circular Flanges PF
49
Joining Clips SS
51
Overcollars MU
53
Duct Measuring Bands MRF
54
Notching Tools NZ and PNZ
19
Round Duct Connections Overview
Ø
mm
Small Circular
Flange Connection
for duct-Ø
80 - 200 mm
in-between Ø
not possible
Overcollars
for duct-Ø
71 - 315 mm
in-between Ø
possible
Circular Flange
Connections
for duct-Ø
200 - 3000 mm
in-between Ø
possible
20
METU-SYSTEM Catalog 6b
Round Duct Connections Overview
Overcollars
for duct-Ø 71 - 315 mm
Overcollar MU
Economical connections for smaller duct diameters.
Flexible, as Ø differences up to 4 mm are covered.
No projections inside the duct (important for the extraction of
dust or wood shavings for example).
Easy installation and dismantling (only one Allen bolt).
No preparation of the duct ends necessary.
Small Circular Flange Connection
for duct-Ø 80 - 200 mm
Circular Flange PF + Joining Clip SS
Pressed flanges for smaller duct diameters.
Fastening through spot welding, drill screws, blind rivets
or swaging.
Swaging eliminates projections inside the duct (important for
the extraction of dust or wood shavings for example).
Easy installation and dismantling through SS Joining Clips.
Circular Flange Connections
for duct-Ø 200 - 3000 mm
The difference between the circular flange types lies in the
way they are connected to the duct. The assembly between
the round air duct components is always made thanks to the
SR Joining Clips.
Circular Flange AF + Joining Clip SR
- Most popular circular flange type.
- With a metal to metal sealing-lip.
- Suitable for spiral ducts and fittings as well as ducts with a longitudinal seam.
- Not suitable for ducts and fittings with a turned-out edge.
- Fastening through notches, drill screws or blind rivets.
Circular Flange UF + Joining Clip SR
- For ducts with stiffening ribs.
- Very good air-tightness, as the end of the duct imbeds
into a soft sealant (not provided)
- Suitable for ducts with important Ø variations.
- Not suitable for ducts and fittings with a turned-out edge.
- Fastening through drill screws or blind rivets.
Circular Flange BF + Joining Clip SR
-
Circular Flange LF + Joining Clip SR
- For ducts and fittings with a turned-out edge.
- Very simple and rapid installation, as the flange snaps onto the turned-out edge of the duct.
- No projections inside the duct (important for the extraction of dust or wood shavings for example).
- Especially suitable for fittings.
Circular Flange MF + Joining Clip SR
- Flange with a solid and simple flange shape.
- Suitable for many different kinds of ductwork.
- Especially suitable for the harsh handling conditions of the mining industry.
- Budget-priced flange.
- Fastening through spot-welding, blind rivets or drill screws.
Round Flexible Connector RFS + Joining Clip SR
- Flexible connection acting as an expansion joint while
eliminating noise and vibrations.
- Tear-resistant and air-tight.
- Without sharp edges to avoid premature wear and tear.
- Easily replaceable fabric.
- Suitable for all usual flexible materials.
METU-SYSTEM Catalog 6b
More flexibility, as the flange enters deeper into the duct.
Duct ends can be inaccurately cut.
Can act as a telescopic fitting.
Brings additional stability to thinner duct walls.
Not suitable for ducts and fittings with a turned-out edge.
Fastening through notches, drill screws or blind rivets.
21
Circular Flanges AF
• Circular flanges with a
sealing-lip having proven their
efficiency literally millions
of times.
• Reduce installation and
assembly costs.
• Bring additional stability to
the duct.
• No additional sealant is required
to reach the DIN EN 12237
air-tightness class C.
• Fasten with notches, self tapping screws or blind rivets.
• Assembly through
SR Joining Clips.
• For duct-Ø 200 up to 3000 mm.
By hammering the flange into the
duct, the tapered sealing lip, whose
diameter is larger than the inner
diameter of the duct, is forced down.
The resulting enormous pressure
between the sealing lip and the duct
wall makes the connection air-tight.
This parallel section is smaller than
the duct Ø and enables the flange
to be centered before being driven
home using a hammer
22
When tightening the SR Joining Clip
two forces come into play: a radial
force centering the flanges, and
an axial force pushing the flanges
against one another.
When SR Joining Clips with gasket
are used, no gasket application on
the flange face is necessary.
This prevents the gasket from
being damaged during installation
and speeds up the assembly.
The notches prevent the flange from
being pulled out. Drill screws and
blind rivets can also be used.
METU-SYSTEM Catalog 6b
Circular Flanges AF
Advantages
Easy Fitting and Assembly:
The AF Circular Flanges are normally fixed into the duct with notches which are created with a manual or a pneumatic
notching tool (more about the notches at the end of this section). The flange is then hammered into the duct and locks
itself beyond the notches, making fitting parts, rivets and tape unnecessary. The flanges can also be fastened using
self-tapping screws or blind rivets. Spot welding is not recommended, as the sealing lip is resilient. The duct sections
are finally assembled together within seconds thanks to an SR Joining Clip (please refer to the „SR Joining Clips“ and
“Nut Runner” sections).
Optimal Stability:
The hollow profile makes the flange light and sturdy at the same time, providing additional stability to the duct by
positive and negative pressures.
AF Circular Flanges Stability, please refer to the Additional Information ZI-602
Air-tightness:
The pressed down sealing lip exerts an enormous pressure onto the duct wall. The result is an air-tight connection up to
Class C according to DIN EN 12237, assuming that the flange fitting and assembly have been carried out correctly.
Characteristics
One set is made of two AF Flanges and one SR Joining Clip
Suitable for:
Spirally
Wound
Duct-Ø
200 to 3000
mm
Fittings
Straight
Seams
Limited
suitability
Dimensions (mm)
(galvanized steel)
Stiffening
Ribs
Not suitable for:
Fittings with
Turned out Edge
Turned out
Edge
C
B
A
H
D
I
G
Three profile sizes:
E
Flange
AF 20 - 45
F
Duct-Ø
200 - 499 mm
A
B
C
D
E
F
G
H
16,4
3,4
0,60
9,0
24,0
1,80
1,60
4,0
I
7,0
AF 50 - 90
500 - 999 mm
26,5
4,2
0,75
12,1
32,0
2,25
1,95
7,3
9,0
AF 100 - 160
1000 - 3000 mm
37,1
5,2
1,00
18,3
46,0
3,00
2,20
8,9
15,0
Dimensions and shape for the AF flanges made of stainless steel:
Additional Information ZI-503.
METU-SYSTEM Catalog 6b
23
Circular Flanges AF
Installation Instructions
1. Duct Diameter Verifications
To ensure the correct functioning of
the AF flanges it is recommended to
check the duct-Ø, at least randomly.
The MRF Measuring Bands allow
you to accurately define the inner
circumference of the duct and
indicate if the duct diameter falls
within the DIN tolerances.
This deviation should be indicated
with your order in order to make
sure that the circular flanges are
manufactured to your exact duct
dimensions.
More information about our MRF
Measuring Bands can be found at the
end of this section.
If not, a graduation indicates the
deviation from the DIN norms
in mm.
2. Creating the Notches
Since the round duct connections are subject to bulking and pulling forces, the round flanges must be fastened into the
duct using notches along the entire circumference of the duct at 100 mm intervals. The distances between notches can
be reduced to 50 mm in case of higher forces. The notches should not be deeper than the sheet metal thickness (max
thickness by galvanized steel 1,5 mm, and 1,2 mm by stainless steel). The distances from the notches to the duct end
must be precise, as well as their shape. This is why we recommend using the following methods for the fastening of
your flanges into the ducts:
Self-tapping
screws
Hand operation:
Hand Notching Tool NZ
Semiautomatic operation:
Pneumatic Notching Tool PNZ
Blind
rivets
Alternatively, the AF circular flanges
can also be fastened with self-tapping
screws or blind rivets.
CAUTION
There are critical areas on the duct ends which must be taken into consideration:
A
A
d1
α
A
B
d1
α
It is not possible to create notches on
seams (A), and have no use when
created on a stiffening rib (B).
24
CAUTION: On larger duct diameters
the seam crosses the end of the duct
at a much smaller angle. The distance
where a notch cannot be created
might therefore be longer than the
prescribed 100 mm (A). In such cases
the flange must be secured with selftapping screws or blind rivets.
Self-tapping screws or blind rivets
must be used on ducts fitted with
stiffening ribs (additional fixing points
might be required). To achieve the
air-tightness class C according to DIN
EN 12237, a sealant must be applied
in the areas where the stiffening ribs
cross the flange.
METU-SYSTEM Catalog 6b
Circular Flanges AF
Installation Instructions
3. Fitting the Flange
A
B
A Enter the parallel section of the AF
circular flange into the duct up to the
start of the tapered sealing lip.
A special grip is available to help in
this operation, especially if the flange
is a tight fit.
B After removing the special grip use
a rubber mallet to drive the flange
home, starting where the flange ends
meet. Assuming that the sealing lip
and the duct wall are undamaged, the
AF Circular Flange ensures an airtight seal up to Class C according to
DIN EN 12237.
On smaller ducts (200 to 499 mm Ø) the seam of the spirally wound or
longitudinal seam ducts might be too high (C), preventing the flange from
being hammered all the way in. In such cases the seam must be ground
down (D) in order to allow the flange to sit properly.
C
D
On round ducts with a longitudinal seam, the sealing lip of the AF flange could
deform the seam and thus expand the duct diameter. Such an occurrence
would negatively affect the stability and tightness characteristics of the
connection. We therefore recommend to spot weld or rivet the seam in the
vicinity of the duct ends.
4. Super Tight Circular Flanges
Correctly installed AF Circular Flanges fulfill the air-tightness requirements of the Class C according to DIN EN 12237.
For higher requirements or if noise generation is a concern (especially with pressures exceeding 1000 Pa), leakage can
be further reduced by using the following methods:
A 100 mm long bead of mastic
applied into the groove of the duct
seam in the position where it crosses
the flange´s sealing lip will reduce
leakage by about 50% and would also
prevent the generation of noise.
A fully air-tight joint is achieved by
applying mastic into the groove of the
flange before it is fitted into the duct.
An alternative way to obtain a fully
air-tight joint is to apply mastic inside
the duct between the flange and the
duct wall as depicted above after the
installation of the flange (not always
practical with smaller ducts).
Air and water tightness of the AF and BF circular flanges:
see Additional Information ZI-601
Installation Instructions (Please refer to the “SR Joining Clips” section)
METU-SYSTEM Catalog 6b
25
Circular Flanges UF
• Connection for circular ducts with reinforcing beads or ribs.
• Suitable for ducts with irregular
diameters.
• Same profile shape as the AF
circular flange, but without the
sealing lip.
• Fastening with self-tapping
screws or blind rivets.
• Assembly using SR Joining Clips.
• For duct-Ø 200 up to 3000 mm.
When tightening the SR Joining Clip
two forces come into play: a radial
force centering the flanges, and
an axial force pushing the flanges
against one another.
Air-tightness is achieved thanks to a
mastic strip inside the profile pocket
in which the end of the duct imbeds
When SR Joining Clips with gasket
are used, no gasket application on
the flange face is necessary.
This prevents the gasket from being
damaged during installation and
speeds up the assembly.
Fastening into the duct
with drill screws or
blind rivets
Instead of applying sealant into the
profile pocket it is possible to apply
sealant inside the duct between the
flange and the duct wall.
26
METU-SYSTEM Catalog 6b
Circular Flanges UF
Advantages
Patented Telescope Technique
A special connecting part acting as a telescope provides support
to the mastic even if the ends of the flange are pulled apart to
accommodate duct diameter variations without weakening the flange.
Economic Assembly
The duct sections are assembled very quickly with a SR Joining Clip
(please refer to the section “SR Joining Clips“).
Air-tightness
The duct end penetrates into the mastic strip, thus providing an air-tight connection fulfilling the Class C
requirements according to DIN EN 12237, even if the duct has stiffening ribs or beads.
Installation Instructions
One set is made of two UF Flanges and one SR Joining Clip
Suitable for:
Stiffening
Ribs
Duct-Ø
Spirally
Wound
Not suitable for:
200 to 3000
mm
Straight
Seams
Dimensions (mm)
(galvanized steel)
Turned out
Edge
Fittings with
Turned out Edge
C
B
A
D
H
F
G
Three profile sizes:
E
Flange
Duct-Ø
UF 20 - 45
200 - 499 mm
A
B
C
D
E
F
G
H
16,4
3,4
0,60
20,6
24,0
1,80
1,60
4,0
UF 50 - 90
500 - 999 mm
26,5
4,2
0,75
27,8
32,0
2,25
1,95
7,3
UF 100 - 160
1000 - 3000 mm
37,1
5,2
1,00
40,8
46,0
3,00
2,20
8,9
Dimensions and shape for the UF flanges made of stainless steel:
please refer to the Additional Information ZI-503.
METU-SYSTEM Catalog 6b
27
Circular Flanges UF
Installation Instructions
1. Sealant Application
Before fitting the UF Circular Flange into the duct, apply a
mastic strip into its pocket as depicted. Alternatively,
sealant can be applied inside the ducts as shown under
step 4 below.
2. Fitting the Flange
Insert the UF Circular Flange into the duct until the duct
wall penetrates into the sealant. A rubber mallet might be
useful.
A
B
On smaller ducts (200 to 499 mm Ø) the seam of the
spirally wound or longitudinal seam ducts might be too
high (A), preventing the flange from being hammered all
the way in. In such cases the seam must be ground
down (B) in order to allow the flange to sit properly.
3. Flange Fastening
Drill Screws
Blind Rivets
The flange can be fastened into the duct with either selftapping screws or blind rivets. Spot welding is not recommended because of the multiple sheet metal layers.
The distance between the fixing points should normally
be 100 mm. For increased load-bearing capacities the
intervals should be reduced to 50 mm.
Flange ends
1 Correct
2 Correct
3 Wrong!
When fixing, start either at the meeting point of the flange
ends and work around (1), or at the opposite point of the
flange ends (2).
CAUTION If you start by fixing both flange ends first, the
duct may become wavy (3)!
4. Sealant Application
An alternative way to obtain a fully air-tight joint is to apply
mastic inside the duct between the flange and the duct
wall as depicted above after installation of the flange.
Not always practical with smaller ducts due to the limited
access.
28
METU-SYSTEM Catalog 6b
Circular Flanges BF
• Wider circular flanges with two
sealing lips providing more
flexibility.
• Duct ends do not need to be
precisely cut.
• Can act as telescope sections.
• Reinforce lighter gauge
ductwork.
• Fastening with notches, selftapping screws or blind rivets.
• Assembly through
SR Joining Clips.
• For duct-Ø 200 up to 3000 mm.
When tightening the SR Joining
Clip two forces come into play: a
radial force centering the flanges,
and an axial force pushing the
flanges against one another.
The angles of the sealing lips are
smaller and the sealing lips are
longer than the ones on the
AF Circular Flange, thus making
installation easier.
When SR Joining Clips with gasket
are used, no gasket application on
the flange face is necessary.
This prevents the gasket from being
damaged during installation and
speeds up the assembly.
This parallel section is smaller than
the duct Ø and enables the flange
to be centered before being driven
home using a hammer.
METU-SYSTEM Catalog 6b
The BF Circular Flange has
been designed for inaccurately
cut ducts. At least one sealing
lip should be inside the duct
and beyond the notches.
The notches prevent the flange
from being pulled out. Self-tapping
screws or blind rivets can also be
used.
29
Circular Flanges BF
Advantages
Fitting and Assembly
As the same technique is used to fasten the AF and BF flanges into the ducts, the information provided in the AF
Circular Flanges section can also be used as a guide for the BF circular flanges. Contrary to the AF flanges, the BF
are made from a wider profile which penetrates deeper into the duct. They are fitted with two sealing lips, although
it is enough that one is firmly secured into the duct. For that reason BF circular flanges can be used on damaged or
inaccurately cut ducts. Because of the variable setting depth, the BF flanges can be used as telescope fittings.
The wider parallel section as well as the wider sealing lips speed up the installation.
Optimal Stability
The especially wide hollow profile provides additional stability to the duct, especially on light gauge ducts which need
additional reinforcements.
Air-tightness
The sealing lips help to seal the duct. On wavy and/or inaccurately cut ducts it is sufficient that one sealing lip is inside
the duct beyond the notches to achieve air-tight connections up to Class C according to DIN EN 12237 (Caution: duct
with stiffening ribs require the application of a sealant).
Installation Instructions
One set is made of two BF Flanges and one SR Joining Clip
Suitable for:
Spirally
Wound
Duct-Ø
Straight
Seams
200 to 3000
mm
Stiffening
Ribs
Dimensions (mm)
(galv. steel)
Not suitable for:
Fittings with
Turned out Edge
Turned out
Edge
Fittings with
Short Ends
D
C
A
G
B
I
H
F
E
Three profile dimensions:
Flange
BF 20 - 45
30
Duct-Ø
200 - 499 mm
A
B
C
D
E
F
G
H
16,0
3,5
12,0
31,0
50,0
1,4
0,60
1,2
I
7
BF 50 - 90
500 - 999 mm
25,7
7,7
15,0
50,0
80,0
1,5
0,75
1,5
9
BF 100 - 160
1000 - 3000 mm
36,3
9,3
20,0
70,0
110,0
2,0
1,00
2,0
15
METU-SYSTEM Catalog 6b
Circular Flanges BF
Installation Instructions
1. Duct Diameter Verifications
To ensure the correct functioning of
the BF flanges it is recommended to
check the duct-Ø, at least randomly.
The MRF Measuring Bands allow
you to accurately define the inner
circumference of the duct and
indicate if the duct diameter falls
within the DIN tolerances.
This deviation should be indicated with
your order in order to make sure that
the circular flanges are manufactured
to your exact duct dimensions.
More information about our MRF
Measuring Flanges can be found at
the end of this section.
If not, a graduation indicates the
deviation from the DIN norms in mm.
2. Creating the Notches
Since the round duct connections are subject to bulking and pulling forces, the round flanges must be fastened into the
duct with notches along the entire circumference of the duct at 100 mm intervals (50 mm in case of higher forces). The
notches should not be deeper than the sheet metal thickness (max thickness by galvanized steel 1,5 mm, and 1,2 mm
by stainless steel). The distances from the notches to the duct end must be precise, as well as their shape.
We recommend the following methods for the fastening of the BF flanges into the ducts:
Self-tapping
Screws
Blind
Rivets
Hand operation:
Hand Notching Tool NZ
Semiautomatic operation:
Pneumatic Notching Tool PNZ
Alternatively, the BF circular flanges
can also be fastened with drill screws
or blind rivets.
CAUTION
There are critical areas on the duct ends which must be taken into consideration:
A
A
d1
α
A
A
d1
α
It is not possible to create notches on
seams (A), and have no utility when
created on a stiffening rib (B).
The width of the BF flanges allows to
find alternative fastening points (A).
METU-SYSTEM Catalog 6b
On larger duct diameters the seam
crosses the end of the duct at a much
smaller angle. The distance where a
notch cannot be created might therefore be longer than the prescribed
100 mm (A). In such cases the flange
must be secured with drill screws or
blind rivets.
Self-tapping screws or blind rivets
must be used on ducts fitted with
stiffening ribs (additional fixing points
might be required). To achieve the
air-tightness class C according to DIN
EN 12237, a sealant must be applied
in the areas where the stiffening ribs
cross the flange.
31
Circular Flanges BF
Installation Instructions
3. Flange Fastening:
A
B
A Enter the parallel section of the BF
circular flange into the duct up to the
start of the tapered sealing lip. The
wide parallel section facilitates the
installation.
B Then use a rubber mallet to drive
the flange home, starting where the
flange ends meet. Assuming that
the sealing lip and the duct wall are
undamaged, the BF Circular Flange
ensures an air-tight seal up to class C
according to DIN EN 12237.
On smaller ducts (200 to 499 mm Ø) the seam of the spirally wound or
longitudinal seam ducts might be too high (C), preventing the flange from
being hammered all the way in. In such cases the seam must be ground down
(D) in order to allow the flange to sit properly.
C
D
On round ducts with a longitudinal seam, the sealing lips of the BF flange
could deform it and thus expand the duct diameter. Such an occurrence would
negatively affect the stability and tightness characteristics of the connection.
We therefore recommend to spot weld or rivet the seam in the vicinity of the
duct ends.
4. Super Tight Circular Flanges
Correctly installed BF Circular Flanges fulfill the air-tightness requirements of the Class C according to DIN EN 12237.
For higher requirements or if noise generation is a concern (especially with pressures exceeding 1000 Pa), leakage can
be further reduced by using the following methods:
A 100 mm long bead of mastic
applied into the groove of the duct
seam in the position where it crosses
the flange´s sealing lip will reduce
leakage by about 50% and would also
prevent the generation of noise.
A fully air-tight joint is achieved by
applying mastic into the groove of the
flange before it is fitted into the duct.
An alternative way to obtain a fully
air-tight joint is to apply mastic inside
the duct between the flange and the
duct wall as depicted above after the
installation of the flange (not always
practical with smaller ducts).
Air and water tightness of the AF and BF circular flanges:
see Additional Information ZI-601
Installation Instructions (Please refer to the “SR Joining Clips” section)
32
METU-SYSTEM Catalog 6b
Circular Flanges LF
• Flange connection for ducts and
fittings with turned out edges
(Van Stone ducts and fittings).
•
Very rapid and economical
installation, as the flange is
simply snapped on the
turned out edge of the duct.
• No projections inside the duct
(ideal for dust extraction).
• Especially suitable for fittings.
• Assembly through
SR Joining Clips.
• For duct-Ø 200 up to 3000 mm.
When tightening the SR Joining Clip
two forces come into play: a radial
force centering the flanges, and
an axial force pushing the flanges
against one another.
The duct´s turned out edge enters
into the tapered opening of the flange.
Air-tightness is achieved through an
injected sealant (hd) which remains
permanently elastic.
When SR Joining Clips with gasket
are used, no gasket application on
the flange face is necessary.
This prevents the gasket from being
damaged during installation and
speeds up the assembly.
Turned out edge of the
duct or fitting.
METU-SYSTEM Catalog 6b
33
Circular Flanges LF
Advantages
Fitting and Assembly
Snapping the flange over a turned out edge is probably the easiest and most economical way of securing a flange onto
a duct, assuming that creating turned out edges does not present any difficulties. This is why the LF circular flanges are
particularly suitable for fittings: they do not modify the length of the ducts and are able to cover more important diameter
tolerances. The duct sections are finally assembled together within seconds thanks to an SR Joining Clip (please refer to
the „SR Joining Clips“ and “Nut Runner” sections).
No Projections inside the Duct
The projections-free connection make the LF Circular Flanges particularly suitable for the extraction or transport of dust,
paper trim, wood chips, etc. Thanks to the SR Joining Clips the duct, sections are also easily removed for cleaning.
Air-tightness
The permanently elastic injected sealant (hd) makes the duct/flange connection air-tight. Class C according to
DIN EN 12237 is achieved, assuming that the flange fitting and assembly have been carried out correctly and the duct
is constructed of the proper gage.
Installation Instructions
One set is made of two LF Flanges and one SR Joining Clip
Suitable for:
Turned out
Edge
Duct-Ø
Not suitable for:
200 to 3000
mm
Fittings with
Turned out Edges
Spirally
Wound
Stiffening
Ribs
Fittings without
Turned out Edges
Dimensions (mm)
(galv. steel)
A
B
Three profile sizes:
C
D
E
Flange
LF 20 - 45
34
Rohr-Ø
200 - 499 mm
A
B
C
D
12,6 mm
0,8 mm
1,0 mm
1,0 mm
E
8,2 mm
LF 50 - 90
500 - 999 mm
21,7 mm
1,0 mm
1,5 mm
1,2 mm
14,0 mm
LF 100 - 160
1000 - 3000 mm
31,0 mm
1,2 mm
2,0 mm
1,5 mm
20,5 mm
METU-SYSTEM Catalog 6b
Circular Flanges LF
Installation Instructions
1. Duct Diameters
For standard ducts, fittings and duct wall thicknesses
according to DIN EN 1506, you can find the corresponding
LF Circular Flanges in the current price list. Please note that
we also supply all intermediate sizes.
In case of doubts regarding the duct-Ø, please refer to the
section “MRF Measuring Bands“.
2. Turned out Edge
The stability of the LF Circular Flange directly depends on
the stability of the duct´s turned out edge. Therefore the
turned out edge should be made as sturdy as possible:
Duct wall thickness
Height of the
turned out edge
LF 20 - 45
LF 50 - 90
LF 100 - 160
Min.
height
Max.
height
5 mm
7 mm
10 mm
7 mm
12 mm
15 mm
Max.
thickness
0,8 mm*
1,0 mm*
1,2 mm*
* Special LF Circular Flanges with wider slots suitable for
thicker turned out edges are available upon request:
- LF 20-45 for max. 1,2 mm sheet metal thickness
- LF 50-90 for max. 1,5 mm sheet metal thickness
- LF 100-160 for max. 2,0 mm sheet metal thickness
3. Fitting the Flange
The LF Circular Flange is snapped on the turned out edge
of the duct or fitting. Start with one end of the flange and
work around.
Should the flange be slightly blocked with its slot on the
turned out edge, use a rubber mallet till the ends of the
flange fit tightly together.
Should a gap remain between both flange ends, the ductØ is too large. You can either measure the precise duct-Ø
by using our MRF Measuring Band and order a
corresponding special LF Circular Flange, or fill the gap
with mastic.
Should the LF Circular Flange be too large, you can either
shorten the flange or order a special LF Circular Flange
after having precisely measured the duct-Ø. For large
diameters the ends of the LF Circular Flange should be
connected with a welding point to keep the flange from
coming off the duct during transport.
METU-SYSTEM Catalog 6b
35
Circular Flanges LF
Load Bearing Capacity
The strength and critical loads of a circular flange connection influence the number and the distance between hangers
and are, for that reason, a significant cost factor. The LF Circular Flanges and the SR Joining Clips are more stable
than the turned out edge of the duct or fitting. The stability of the connection depends therefore directly on the turned
out edge which should be as stable and as high as possible.
Example: One needs a 1700 kg pulling force to tear apart an assembly of
two LF flanges and an SR Joining Clip installed on a 500 mm duct
diameter with a duct wall thickness of 1 mm and a turned out
edge height of 10 mm.
Caution:
In a negative pressure environment the LF flanges do not provide
any additional stability to the duct. It is furthermore recommended
to create a stiffening rib running parallel to the LF flange for
extra stability.
Air-tightness
The turned out edge of the duct penetrates into the sealer in the slit of the LF Circular Flange, thus creating an air-tight
connection. Furthermore, the ends of the LF flanges are pressed against one another because of the pressure applied
by the SR joining clips. That way the LF flange is fixed onto the duct in an air-tight manner.
During the assembly, the SR joining clip fitted with a gasket creates an air-tight connection. Should the SR joining clip
be without gasket, a self-adhesive gasket would have to be applied on the face of one of the LF flanges.
A correctly installed connection made of two LF Circular Flanges with an SR Joining Clip exceeds, without additional
work, the air-tightness class C according to DIN EN 12237.
HD Sealant Specifications: see the Additional Information ZI-401.
LF Flanges made of Stainless Steel (V2A)
Air Tightness
The LF circular flanges made of stainless steel come without hd sealant for the
following reasons:
The stainless steel material is delivered with a protective foil on one side,
which also facilitates the profiling of the flange. During the LF forming process
this foil is stuck inside the profile as well as inside the slit where the sealant is
injected on the galvanized steel versions. As parts of that protective foil detach,
they carry away the hd sealant which has been applied on them (fig. 1). In
such cases, to make sure that the air tightness class C (DIN EN 12237) is
reached, additional sealant should be applied as indicated on fig. 2.
1
Sealant
2
Foil
Operating Temperatures
It is important to keep in mind that the protective foil inside the LF flange
might create problems for applications above 100 °C, as the foil would melt
or eventually burn.
Version for 1000 mm Duct-Ø
The LF 1000 mm Ø made of stainless steel V2A are manufactured from the
medium profile and not the large one.
Installation Instructions (Please refer to the “SR Joining Clips” section)
36
METU-SYSTEM Catalog 6b
Circular Flanges MF
• Solid and simple flange shape.
• Suitable for many different kinds
of ductwork.
•
Especially suitable for
the rough handling
conditions in the
mining industry.
• Budget-priced flange.
• Fastening through spot-welding,
blind rivets or drill screws.
• Flange can be installed inside or
outside the duct.
• Assembly through SR Joining
Clips.
• For duct-Ø 200 up to 3000 mm.
International
Patents
When tightening the SR Joining
Clip two forces come into play:
a radial force centering the flanges,
and an axial force pushing the flanges against one another.
Air-tightness is achieved through a
mastic strip that is applied during
the installation process and in
which the end of the duct imbeds.
The flange is secured in the
duct by either spot-welding,
blind rivets or self-tapping
screws.
METU-SYSTEM Catalog 6b
When SR Joining Clips with gasket
are used, no gasket application on the
flange face is necessary. This prevents
the gasket from being damaged during
installation and speeds up assembly.
As an alternative the mastic
can be applied inside the duct
between the circular flange and
the duct wall.
37
Circular Flanges MF
Advantages
Sturdy & budget-priced
The flange´s simpler profile and the thicker material make it less sensible to harsh handling conditions.
It is therefore especially suitable for the mining industry.
The flange fitting is more laborious compared to an AF-flange (mastic must be applied), but the purchase price is
lower.
Economic Assembly
The duct sections are assembled very quickly with a SR Joining Clip
(please refer to the section “SR Joining Clips“).
Air-tightness
The duct end penetrates into the mastic strip, thus providing an air-tight connection fulfilling the Class C
requirements according to DIN EN 12237, even if the duct has stiffening ribs or beads.
Features
One connection is made of:
2 MF Circular Flanges and 1 SR Joining Clip
Suitable for:
stiffening
ribs
duct-Ø
200 to 3000
mm
spirally wound
fittings with
turned out edge
There are three MF Circular Flange profile sizes:
A
B
E
38
turned out
edge
straight seam
Dimensions:
(galvanized version)
D
Not suitable for:
C
A
B
C
D
E
MF 20-45
MF 50-90
for duct-Ø
for duct-Ø
for duct-Ø
200-499 mm
500-999 mm
1000-3000 mm
6,9
14,0
20,0
1,0
5,0
mm
mm
mm
mm
mm
11,3
23,2
28,0
1,2
8,0
mm
mm
mm
mm
mm
MF 100-160
16,7
34,0
42,0
2,0
11,0
mm
mm
mm
mm
mm
METU-SYSTEM Catalog 6b
Circular Flanges MF
Installation Instructions
1. Mastic application:
Before fitting the MF Circular Flange into the duct,
apply mastic into its pocket as depicted, unless
the mastic is applied after the flange has been
installed (please refer to 5.).
2. Fitting the Flange:
Insert the MF Circular Flange into the duct until the
duct wall penetrates into the sealant.
A rubber mallet might be useful.
3. Fixing Methods (the flange can be installed inside or outside the duct):
Spot-welding
- Only small projections inside the
duct.
- Painting against corrosion might
be required.
Self-tapping screws
- The screws create projections
inside the duct.
This may not be allowed.
Blind rivets
- Strong but relatively expensive
fixing method.
- Only small projections inside the
duct.
4. When fixing the MF Circular Flanges into the duct, either start at the meeting point of the flange ends
and work around (1) or at the opposite point of the flange ends (2).
If you start by fixing both flange ends first, the duct may become wavy (3)!
1
meeting point
of the
flange
ends
correct
2
correct
meeting point
of the
flange
ends
3
meeting
point
of the
flange
ends
wrong!
5. Alternative Mastic Location
An alternative to obtain an air-tight connection is
to apply mastic inside the duct between the flange and the duct wall as depicted (not always feasable
on small duct-Ø).
METU-SYSTEM Catalog 6b
39
Joining Clips SR
• For the assembly of the AF, UF,
BF, LF and MF circular flanges.
• Easy and rapid installation.
• Available with or without gasket.
• For duct-Ø 200 up to 3000 mm.
Shell
Curved Bolt
H
The ends of the
Joining Clip overlap
and compress that
way the ends of the
self-adhesive gasket
against one another
(only on SR Joining
Clips with gasket)
1
H Values for:
SR 20 - 45 ≈ 35 mm
SR 50 - 90 ≈ 45 mm
SR 100 - 160 ≈ 65 mm
A SE Nut Runner
fitted on an impact
wrench allows rapid
tightening of the nut.
2
When tightening the SR Joining Clip
two forces apply:
1. a radial force centering
the flanges, and
2. an axial force pushing the
flanges against one another.
40
METU-SYSTEM Catalog 6b
Joining Clips SR
Applications
Duct Connection with AF Circular Flanges
Duct Connection with UF Circular Flanges
Duct Connection with BF Circular Flanges
Duct Connection with LF Circular Flanges
Different circular flange types
having identical diameters
can be connected together
thanks to the SR Joining Clips!
Duct Connection with MF Circular Flanges
Dimensions
Three profile sizes:
A
C
B
D
E
F
Galv.
steel
version
A
B
C
D
E
F
Nut
SR 20-45
SR 50-90
for Duct Ø
for Duct Ø
SR 100-160
for Duct Ø
200-499 mm
500-999 mm
1000-3000 mm
5,9 mm
5,0 mm
0,8 mm
9,3 mm
14,9 mm
16,2 mm
M6
8,4 mm
7,2 mm
1,0 mm
15,0 mm
23,4 mm
25,1 mm
M8
12,1 mm
10,4 mm
1,5 mm
22,6 mm
34,8 mm
37,4 mm
M12
SR Joining Clip with Gasket
Since it is not necessary to apply a gasket on the circular
flange face, the SR with gasket offer the following
advantages:
- Labor and time savings on site.
- The gasket is inside the groove of the Joining Clip.
This prevents the gasket from being damaged during installation and speeds up the assembly.
- Trouble-free removal possible.
- The gasket is applied under ideal conditions in our
factory (no dirt, extreme temperatures or humidity).
A
B
METU-SYSTEM Catalog 6b
PE Gasket Dimensions
A
B
for Duct Ø
for Duct Ø
for Duct Ø
200-499 mm
500-999 mm
1000-3000 mm
5,0 mm
7,0 mm
6,0 mm
10,0 mm
8,0 mm
14,0 mm
Standard Version: SR Joining Clips with PE
come with a self-adhesive polyethylene foam gasket (grey).
Operating temperature up to +60°C.
For Higher Temperatures: SR Joining Clips with KF
come with a self-adhesive vitreous fiber gasket.
Operating temperature up to approx. +200°C
Additonal Information:
Polyethylene (PE) gasket specifications: ZI-202
Vitreous fiber (KF) specifications: ZI-206
Steel specifications: ZI-101
41
Joining Clips SR
Installation Instructions
1
Only when SR Joining Clips without gasket are used:
Apply the gasket in the middle of the flange face as
depicted. More information about suitable gaskets can
be found in the section on “Gaskets”.
We recommend to using SR Joining Clips with gasket (in
which case step 1 is no longer needed), as the gasket
application on site cannot be done under ideal conditions.
Furthermore, the gasket when applied on the face of the
flange could be damaged during the assembly process.
2
3
4
Hang the SR Joining Clip over the flange.
Insert the next duct section into the lower half of the SR
Joining Clip and raise the opposite end until both flanges
are pretty much parallel.
Finally, tighten the SR Joining Clip using a SE Nut Runner
(see opposite page) fitted on an impact wrench.
Interrupt the tightening process several times and hammer
the Joining Clip slightly with a rubber mallet to ensure a
tight fit on the flanges.
Please note the max. torque figures of the nut:
SR 20- 45 galv.: 3,0 Nm
SR 50- 90
galv.:15,0 Nm
SR 100-160
galv.: 50,0 Nm
For SR Joining Clips made of Stainless Steel:
A lubricating, anti-seize compound for stainless steel parts
(i.e. TECCEM AHT415) should be used on stainless steel
nuts and bolts. The tightening should be carried out
carefully and by hand.
5
Bands or shells which surround the duct enable secure
and economical duct hanging.
Very economical duct hanging can be accomplished
with “RS Circular Duct Supports“ and “BA Circular Duct
Supports“. These products are available with and without
sound isolation.
42
METU-SYSTEM Catalog 6b
Joining Clips SR
SR Joining Clip with Lever
≈ 33 mm
≈ 73 mm
We suggest using the SR Joining Clip with lever only if the
ducts must be dismantled on a regular basis.
Furthermore, this version can only be installed on small duct
diameters from 200 up to approximately 400 mm.
Above 400 mm diameters the lever system might not be
strong enough to sufficiently compress the gasket.
M6 x 60
Nut Runners SE
• For the tightening of the SR Joining Clip bolt
within seconds.
• The hollow body of the SE Nut Runner
provides sufficient clearance for the
curved SR Joining Clip bolt.
• Suitable for all commonly used electric and
pneumatic tools.
The tool is made of galvanized
steel to prevent corrosion.
The nut can be tightened
continuously to the end
of the thread.
The body is hollow to accommodate
the curved SR Joining Clip bolt.
Different SE Nut Runners versions
are available for a range of standard
square drive socket sets.
The curve is adapted to the
SR Joining Clip radius ranges.
Designation
Art. No.
G03A-1001
G03A-1002
G03A-1003
G03A-1004
G03A-1005
G03A-1006
G03A-1007
G03A-1008
G03A-1009
G03A-1010
G03A-1011
Description
SE M 6 - 1/4”
SE M 6 - 3/8”
SE M 6 - 1/2”
SE M 8 - 1/4”
SE M 8 - 3/8”
SE M 8 - 1/2”
SE M 8 - 3/4”
SE M 12 - 3/8”
SE M 12 - 1/2”
SE M 12 - 3/4”
SE M 12 - 1”
METU-SYSTEM Catalog 6b
Application
for Joining Clips
for Joining Clips
for Joining Clips
for Joining Clips
for Joining Clips
for Joining Clips
for Joining Clips
for Joining Clips
for Joining Clips
for Joining Clips
for Joining Clips
SR
SR
SR
SR
SR
SR
SR
SR
SR
SR
SR
20 - 45 /
20 - 45 /
20 - 45 /
50 - 90 /
50 - 90 /
50 - 90 /
50 - 90 /
100 - 160 /
100 - 160 /
100 - 160 /
100 - 160 /
duct-Ø
duct-Ø
duct-Ø
duct-Ø
duct-Ø
duct-Ø
duct-Ø
duct-Ø
duct-Ø
duct-Ø
duct-Ø
200 to 499 mm
200 to 499 mm
200 to 499 mm
500 to 999 mm
500 to 999 mm
500 to 999 mm
500 to 999 mm
1000 to 3000 mm
1000 to 3000 mm
1000 to 3000 mm
1000 to 3000 mm
43
Round Flexible
Connections RFS
• Eliminate vibrations and noise
transmissions and act as
expansion joints.
• Connection with other
METU-SYSTEM flange types
with SR Joining Clips.
• Can be fitted with most
commonly used flexible
materials.
• You can assemble the Flexible
Connector yourself or you can
order the Flexible Connector
assembled and ready for
installation.
No sharp edges
which could damage
the fabric.
The AF Flange sealing lip provides
additional security against pulling-off.
Duct wall
Most flexible materials can be used.
Sturdy, roll-formed RSB Tension
Band made of galvanized steel.
An AF Circular Flange is
customarily used and can be
easily connected with other
METU-SYSTEM Circular Flanges.
44
The flexible material can
be easily replaced thanks
to a tension lock.
METU-SYSTEM Catalog 6b
Round Flexible Connections RFS
Installation Instructions
If you buy already assembled RFS Flexible Circular Connectors:
An assembled RFS Flexible Circular Connector is made of:
2 AF Circular Flanges, 2 RSB Tension Bands and the flexible material.
Standard flexible material Additional Information: ZI-308.
The connection to the duct work, or between the duct work and some other equipment such as a fan,
is then easily and rapidly done using SR Joining Clips.
If you assemble the RFS Flexible Circular Connectors yourself:
1. Required parts
a)
b)
c)
d)
a
b
c
b
a
2 AF or UF Circular Flanges corresponding to the duct-Ø.
2 RSB Tension Bands for the same Ø as above.
1 flexible material sleeve.
2 intercalation plates.
2. Flexible material sleeve execution
a) Material:
The flexible material has to be chosen according to the relevant requirements such as operating
pressure, temperature, mechanical and chemical resistance, etc.
b) Length:
You have to add 20 to 40 mm to the required installation length L1 for the folding of the material.
The stretched length L2 is therefore L1 + 20 to 40 mm.
Because of the Circular Flanges the sleeve has to be a bit shorter than the stretched length L2:
- RFS 20 to 45:
stretched length minus 7 mm (for both Circular Flanges)
- RFS 50 to 90:
stretched length minus 9 mm (for both Circular Flanges)
- RFS 100 to 160:
stretched length minus 11 mm (for both Circular Flanges)
Recommended L1 Length
RFS
L1
L2
L3
L4
20- 45
80
107
100
59
50- 90
100
133
124
69
100-160
120
160
149
68
(mm)
L2
L4
L3
c) Circumference: The circumference of the flexible material
should be such that the sleeve fits tightly
around the sealing lip of the AF Circular Flange.
d) Seam:
An overlapping welded seam is commonly used. For this reason attention should be paid to the material thickness: the thicker the fabric, the larger the gap created where the edges overlap. An appropriate sealant like mastic should therefore be applied in this area. Stitched seams should be made absolutely air-tight. It is also important that the flexible material remains flexible,
including in the seam area.
METU-SYSTEM Catalog 6b
45
Round Flexible Connections RFS
Installation Instructions
3. Assembly
a) Lay one of the AF Circular Flanges (A) on a table and pass the fabric sleeve (B)
around the AF flange and over the AF sealing lip until it touches the bottom of the AF pocket (C). We recommend to place the fabric´s seam at the same A
position where both ends of the AF Circular Flange meet. The Tension Lock
of the RSB Tension Band should also be placed in that position.
B
C
b) Leaks may occur at three places:
1. The overlapping seam does not allow the fabric to be in constant contact
with the circular flange, especially if thick fabric materials are used.
2. There is a small gap where both ends of the circular flange meet.
3. When tightening the RSB Tension Band a fold may eventually appear
if the intercalation plate has not been installed properly.
c) Place the RSB Tension Band over the fabric sleeve until it touches the
bottom of the Circular Flange pocket.
B
A
The RSB Tension Band is installed correctly when its upper edge is at the
same level as the upper edge of the Circular Flange (B).
d) The RSB Tension Ring should be tightened until a gap of 1 to 2 mm remains between the RSB ends. Place the
intercalation plate at this point underneath the gap, flush with the upper edge of the RSB Tension Band, and finish tightening the Tension Lock (do not over-tighten, as this might deform the hook). Please note that if the
intercalation plate is not installed, a fold may eventually appear and create leakage.
A
B
C
D
E
F
G
=
=
=
=
=
=
=
SR Joining Clip
AF Circular Flange
RSB Tension Band
Flexible material sleeve
Intercalation plate
AF Circular Flange
Duct interior
A
B
C
D
E
F
G
The same procedure should be followed to finish
the other side of the Flexible Circular Connector.
46
METU-SYSTEM Catalog 6b
Circular Flanges PF
• Cost effective circular flange
for small duct diameters.
• Pressed flange which can be
swaged into the duct. That way
the duct inner surface remains
free of any projections (for dust
removal, wood chips transport
and other similar applications
requiring a smooth inner duct
surface)
• Alternative fastening methods: spot welding, self-tapping
screws or blind rivets
• Assembly through
SS Joining Clips.
• For duct-Ø 80 up to 200 mm.
When tightening the SS Joining Clip
two forces come into play: a radial force
centering the flanges, and an axial force
pushing the flanges against one another.
If the flange is not swaged into the
duct, a mastic strip in which the duct
wall imbeds should be applied here
to ensure air-tightness
When SS Joining Clips with gasket
are used, no gasket application on
the flange face is necessary. This
prevents the gasket from being
damaged during installation and
speeds up the assembly.
Swaging is an economical fixing
method which provides a
projection-free duct interior.
Other fixing methods such as selftapping screws, spot welding or
blind rivets are also possible.
METU-SYSTEM Catalog 6b
47
Circular Flanges
PF
Installation Instructions
One set is made of two PF Flanges and one SS Joining Clip
Suitable for:
Spirally
Wound
Duct-Ø
Straight
Seams
Not suitable for:
80 to 200
mm
Stiffening
Ribs
Fittings with
Turned out Edge
Turned out
Edge
Dimensions (mm) for the version in galv. steel
Flange
Duct-Ø
PF 8 - 20
80 - 200 mm
A
A
B
C
D
5,0 mm
9,8 mm
4,0 mm
16,0 mm
E
B
0,8 mm
C
E
D
1. Mastic Application
When the PF Circular Flange is not swaged into the duct,
apply mastic into its pocket as depicted before fitting the
flange.
Normally there is no need to apply any sealant if the
flange is swaged into the duct, assuming that all parts
are precisely manufactured and undamaged. In case of
doubt, it is recommended to apply some mastic.
Swaging is a particularly effective method to
secure the PF Circular Flanges in the duct:
- The process is economical.
- Good air-tightness is achieved without
mastic (please see point 1 above).
- There are no projections inside the duct.
2. Fastening
Other fixing methods such as self-tapping screws,
spot-welding or blind rivets can also be used.
A
48
B
The seam can occasionally be too high on some spirally
wound (A) or longitudinally seamed round ducts,
preventing the flange from being properly inserted into the
duct. In such cases the seam must be ground down (B) in
order to allow the flange to sit properly.
METU-SYSTEM Catalog 6b
Joining Clips SS
• For the assembly of the
PF circular flanges.
• Using special indents the
SS Joining Clips can be easily
opened for faster installation.
• Rapid assembly using a
unique bolt.
• The tension lock also allows the
easy removal of the duct.
• Available with or without gasket.
• For duct-Ø 80 up to 200 mm.
Tension Hook
M4 Allen Screw which can
be tightened using a power
screw driver or a hand
socket wrench.
Tension Allen Screw
The Joining Clip ends
overlap and compress the
ends of the self-adhesive
gasket (only for the
SS Joining Clips
with Gasket).
Indents allowing
to open the SS
Joining Clip widely
1
2
When tightening the SS Joining Clip
two forces apply:
1. a radial force centering
the flanges, and
2. an axial force pushing
the flanges against one another.
METU-SYSTEM Catalog 6b
49
Joining Clips SS
Installation Instructions
1. Only if SS Joining Clips without gasket are used, apply the gasket in the middle of the PF Circular Flange face.
2. Open the SS Joining Clip by loosening the Allen Bolt and unhook it.
3. Align the duct segments and place the SS Joining Clip over both PF Circular Flanges.
4. Hook the Allen Bolt and tighten it.
Maximum torque figures of the bolt:
SS Joining Clips galvanized:
1,5 Nm
SS Joining Clips stainless:
2,0 Nm
Do not over-tight, as this might deform the hook!
For SS Joining Clips made of Stainless Steel:
A lubricating, anti-seize compound for stainless steel parts
(i.e. TECCEM AHT415) should be used on stainless steel
nuts and bolts. The tightening should be carried out
carefully and by hand.
Caution:
The SS Joining Clips are not intended to be opened and
closed frequently, as the material where the indents have
been created can become weak, and even break.
Dimensions
A
Galvanized Steel
F
C
B
The following dimensions (mm) are valid for the SS
Joining Clips from 8 to 20 (Duct Ø 80 to 200 mm)
D
E
A
B
C
D
E
F
4, 9
6,3
4,0
10,4
11,7
0,8
Allen Key M4
Joining Clips with Gasket
Since it is not necessary to apply a gasket on the circular flange face, the SS with gasket offer the following
advantages:
- Labour and time savings on site.
- The gasket is inside the groove of the Joining Clip.
This prevents the gasket from being damaged during installation and speeds up the assembly.
- Trouble-free removal possible.
- The gasket is applied under ideal conditions in our
factory (no dirt, extreme temperatures or humidity)
50
Standard Version
The SS Joining Clips with PE come with a self-adhesive
polyethylene foam gasket (5 × 3 mm, grey). Operating
temperatures up to +60°C.
For Higher Temperatures
The SS Joining Clips with KF come with a self-adhesive
vitreous fibers gasket. Operating temperatures up to
approx. +200°C
Additional Information:
Polyethylene (PE) gasket specifications: ZI-202
Vitreous fibers gasket (KF) specifications: ZI-206
Steel specifications: ZI-101
METU-SYSTEM Catalog 6b
Overcollars MU
• Economical connection for small
duct diameters.
• One-bolt fixing system
ensures a rapid and trouble-free
assembly.
• Flexible: differences up to 4 mm
in duct diameters are covered.
• No projections inside the duct
(dust extraction, grinding).
• Inaccurate duct ends are securely
connected.
• Can be easily disassembled.
• No preparation of the duct ends
necessary.
• For duct-Ø 80 up to 200 mm.
• For heavy gauge ducts, larger
than 315 mm diameters also
available upon request.
Standard gasket made of polyethylene
foam. Other gaskets for special
requirements (i.e temperatures up to
200°C) available upon request
The gasket´s elasticity seals
even the external seam
of spirally wound duct work
The rounded ends and the angled
gasket facilitate the insertion of
the duct.
When the MU Overcollar is tightened,
the two ends of the ducting are
clamped metal against metal.
Equipotential bounding see Additional Information ZI-703
METU-SYSTEM Catalog 6b
51
Overcollars MU
Applications
Suitable for:
Spirally
Wound
Duct-Ø
Straight
Seam
Fittings
Not suitable for:
71 to 315
mm
Turned out
Edge
Formstücke
mit Bord
Fittings with
Turned out Edge
The MU Overcollar is not suitable for duct-Ø larger than 315 mm, because the radial pressure exerted by the
Overcollar may deform the ductwork. Exceptions are double-walled and heavy gage ductwork for which larger
MU Overcollar diameters are available upon request.
Stability:
When the Overcollar is fully tightened, the duct work is held rigid, both longitudinally as well as to impede deflection
or bending.
The tensile strength in the axial direction is very high. On a smooth duct wall of 100 mm duct-Ø for instance,
110 kg are necessary to separate the ducts. The separation force required is much higher for larger diameter duct
work and spirally wound duct work. This rigidity is a fundamental benefit when compared with simple push-in
connectors. It simplifies the installation of the duct work while enabling considerable cost and time savings!
Air-tightness:
Tests conducted by the independent English BSRIA Institute are proving the fact that correctly installed
MU Overcollars on good quality duct work reach Class D air-tightness requirements according to DIN EN 12237.
For normal applications the Class C requirements are reached without difficulty.
Because of the very large gasket surface the seal remains efficient even if the ends of the duct are not fully
inserted (min. 20 mm are necessary), if they are not squarely cut, or if they are damaged at some places.
There is a very small gap along one side of the duct seam on spirally wound duct work which cannot be fully sealed by
the gasket. To achieve higher air-tightness requirements just apply some mastic at one point along the seam.
Pressure classes:
Using MU Overcollars with higher pressures is only limited by the stability and roundness of the duct work.
For normal, non-damaged ducts, the following pressures are applicable:
3.000 Pa positive pressure inside the duct: from duct-Ø 71 up to 315 mm
2.000 Pa negative pressure inside the duct: from duct-Ø 71 up to 150 mm
1.000 Pa negative pressure inside the duct: from duct-Ø 71 up to 315 mm
Drag and noise:
Because the duct ends are embedded in the gasket there are no projections inside the duct which could hinder the
air flow. Therefore noise and dirt accumulations are avoided. Furthermore the air flow direction does not need to be
taken into consideration.
Installation Instructions
Fitting the MU Overcollar is very simple: push both duct sections inside the Overcollar
making sure that a distance between 8 mm (min.) and 25 mm (max.) is left between the
duct ends. The insertion depth should be approximately the same for each duct
section. Duct-Ø differences up to 4 mm are covered. The Overcollar can be rotated
before tightening the clamping bolt for esthetical or practical purposes. Tighten the
clamping bolt forcefully using an impact wrench, power screwdriver or hand socket
wrench until the peened over ends of the Overcollar are tight to the duct, metal to metal.
The overcollar edges should be embedded into the duct seams. If needed the clamping
bolt can be shortened by cutting. Maximum torque: 5 Nm.
MU Overcollars made of Stainless Steel: A lubricating, anti-seize compound for stainless
steel parts (i.e. TECCEM AHT415) should be used on stainless steel nuts and bolts. The
tightening should be carried our carefully and by hand.
Dimensions
90,6 mm
4,2 mm
52
Galvanized
steel
METU-SYSTEM Catalog 6b
Duct Measuring
Bands MRF
• For the precise measurement
of the inner duct diameters
according to DIN EN 1506.
• Since the diameter of light
gauge and/or larger ducts might
be difficult to assess, the inner
circumference of the ducts is
measured.
• Eventual diameter variations
(+ or -) can be read on a scale.
• Made of lacquered spring steel.
Utilization Instructions
Fix the end of the Measuring Band which has the printed scale inside the duct, using the supplied clamp. This leaves
both hands free to feed the Measuring Band around the circumference and parallel to the duct end.
The inner circumference can be then read to an accuracy of 0,5 mm.
The MRF Measuring Bands have been designed for ducts manufactured to DIN EN 1506. The black mark on the scale
indicates the precise DIN EN 1506 dimension and the red mark the maximum permissible dimension. METU-SYSTEM
Circular Flanges can be used if the duct is within the shown tolerance.
Should the circumference be outside the tolerance, the deviation from the standard circumference is
indicated in mm. By mentioning this deviation when ordering will allow us to manufacture the correct
flange size.
The end of the Measuring Band shows DIN -20 mm, mean-
Example 1:
ing that the duct is 20 mm smaller in circumference than a duct
manufactured to DIN EN 1506. A special flange of Ø 355 minus
20 mm circumference is to be ordered.
The end of the Measuring Band shows DIN +20 mm, meaning
Example 2:
that the duct is 20 mm larger in circumference than a duct
manufactured to DIN EN 1506. A special flange of Ø 355 plus 20
mm circumference is to be ordered.
The end of the Measuring Band shows an accurate reading
Example 3:
according to DIN EN 1506. A standard Ø 355 mm can therefore
be ordered.
Designation
Art. No.
G01V-1001
G01V-1002
G01V-1003
G01V-1004
G01V-1005
G01V-1006
G01V-1007
G01V-1008
G01V-1009
G01V-1010
Descr.
MRF 7
MRF 8
MRF 9
MRF 10
MRF 11
MRF 12
MRF 14
MRF 15
MRF 16
MRF 18
METU-SYSTEM Catalog 6b
for Duct Ø
70 mm
80 mm
90 mm
100 mm
112 mm
125 mm
140 mm
150 mm
160 mm
180 mm
Art. No.
G01V-1011
G01V-1012
G01V-1013
G01V-1014
G01V-1015
G01V-1016
G01V-1017
G01V-1018
G01V-1019
G01V-1020
Descr.
MRF 20
MRF 22
MRF 25
MRF 28
MRF 30
MRF 31
MRF 35
MRF 40
MRF 45
MRF 50
for Duct Ø
200 mm
224 mm
250 mm
280 mm
300 mm
315 mm
355 mm
400 mm
450 mm
500 mm
Art. No.
G01V-1021
G01V-1022
G01V-1023
G01V-1024
G01V-1025
G01V-1026
G01V-1027
G01V-1028
G01V-1029
G01V-1030
G01V-1031
Descr.
MRF 56
MRF 60
MRF 63
MRF 71
MRF 80
MRF 90
MRF 100
MRF 112
MRF 125
MRF 140
MRF 160
for Duct Ø
560 mm
600 mm
630 mm
710 mm
800 mm
900 mm
1000 mm
1120 mm
1250 mm
1400 mm
1600 mm
53
Notching Tools
NZ and PNZ
•
For the creation of notches
at the correct distance from the
duct end and with the correct
depth for the secure fastening
of the AF and BF circular
flanges.
• Choice between hand or
pneumatically operated notching
tools.
• Interchangeable high quality
cutters guarantee a long life
expectancy.
Shape of the Notches
AF or BF 20 to 45 = 7 mm
AF or BF 50 to 90 = 9 mm
AF or BF 100 to 160 = 15 mm
Duct wall thickness
4 times the
duct wall
thickness
Duct End
One time the duct wall
thickness
Galv. Steel.:
max. 1,5 mm,
Stainless Steel:
max. 1,2 mm
The notch must protrude inside the duct!
Designation
Art. No.
Description
for duct Ø
G02V-1001
Hand Notching Tool NZ AF 20 - 45 200 to 499 mm
G02V-1002
Hand Notching Tool NZ AF 50 - 90 500 to 999 mm
G02V-1003
Hand Notching Tool NZ AF 100 - 160
G02V-1004
Pneumatic Notching Tool PNZ AF 20 - 160 1000 to 3000 mm
200 to 3000 mm
54
METU-SYSTEM Catalog 6b
Notching Tools NZ and PNZ
Hand Notching Tools NZ
Comfortable and robust hand-operated notching tools with
hardened, interchangeable cutters.
The body is designed to provide a wide-end stop surface
to ensure that the notch is not only at the correct distance,
but at the right angle as well.
Sufficient leverage allows the tool to be used with very
little effort.
There are three Hand Notching Tool sizes:
for AF and BF 20 - 50 (duct-Ø 200 to 499 mm)
for AF and BF 50 - 90 (duct-Ø 500 to 999 mm)
for AF and BF 100 - 160 (duct-Ø 1000 to 3000 mm)
Upper cutter
Lower cutter
Operating instructions: Start by using scrap material
having the same thickness as your duct wall to test the
notch quality. The depth of the notch must correspond
to the duct wall thickness. Corrections can be made by
adjusting the stop screw. Under normal operating
conditions the cutters have a very long life. If the upper
cutter becomes slightly blunt it may be reground a little.
By doing so, do not modify the cutter thickness, since this
would affect the cutting clearance. The lower cutter can
be used in four positions and therefore hardly needs to be
reground. Applying occasionally a few drops of oil in the
joints will extend the tool’s life expectancy considerably.
Pneumatic Notching Tools PNZ
This robust pneumatic-hydraulic notching tool allows a
fatigue-free, comfortable and rapid operation.
The cutter head is robust but still leaves the cutting area
in clear view.
The stops can be interchanged so that the same tool can
be used for all AF and BF Circular Flange diameters
(from 200 mm up to 3000 mm).
Stops depending on
the diameter ranges
Storage for stops
not in use
Trigger
M8 screw for
adjusting the
depth of the
notches
Operating instructions: After having fitted the correct stops
use scrap material having the same thickness as your
duct wall to test the notch quality. The depth of the notch
must correspond to the duct wall thickness. Corrections
can be made by adjusting the M8 screw at the draw bolt.
With regard to regrinding the cutters the same principles
apply as to the Hand Notching Tools above.
The interchangeable stops storage place is located in the
tool´s rear casing.
The pneumatic notching tool requires an air pressure of
4-6 bar and a filter lubricator unit must be fitted to the
air line.
Please read the owner´s manual carefully!
METU-SYSTEM Catalog 6b
55