Rectangular Duct Connections - METU Meinig AG Catalog 6b 9 Rectangular Duct Connections M2 M3 M4...

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METU-SYSTEM Catalog 6b

Rectangular Duct Connections

M2 + M3 + M4 Rectangular Flanges

Corner Pieces for Formed-on Flanges

8 METU-SYSTEM Catalog 6b

• 4-Bolt connection system with an external bead for the easy installation of clamps.

• The METU-SYSTEM triangular shape provides an

optimal flange stability.

• Well engineered clamps allow an easy and efficient installation.

• Available in 20, 30 and 40 mm profile heights.

• Also available with injected sealant (hd version).

The upturned leading edge on some profiles allows the flange to easily

pass onto the duct wall

The angled section of the profile provides additional rigidity (resistance against traction in the corner piece areas, and against compression generated by the gasket between the corners)

The “hd” version of the profiles has an injected soft sealant into which the edge of the duct imbeds

The edge of the duct serves as a stop when fitting the flange frame, thus avoiding distortion or bowing of the profile sectionThe dished internal web presses

against the duct wall, acting as a metallic self-sealing lip

The bead on the external web of the profile section simplifies

the fitting of clamps

Rectangular Flanges M2 M3 M4

9METU-SYSTEM Catalog 6b

Rectangular Duct Connections M2 M3 M4

Air-tightness Influences the: - energy consumption - noise generation - air quality

The most important aspects of a rectangular duct work connection

Profile Deflection Influences the - efficiency and integrity - applications range - appearance

Corner Piece Strength Influences the - air-tightness after installation - required number of clamps - required number of supports

Gaping: Influences the - air-tightness - appearance - required number of supports

The above mentioned criteria determine the performance, quality and appearance of your ductwork. Not all rectangular connections are created equal!

Prominent edge in the corner area

Hollow triangular profile

Triangular shape for maximum rigidity

Lateral supporting side increasing the resistance against torsion

Sealing lip

Press-formed corners

The METU Answer

The METU Answer

The METU Answer

The METU Answer

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Corner Pieces


The METU-SYSTEM corner pieces are exceptionally robust, as they are made of a thick material which has been deep press-formed to confer them a shape making them even sturdier.

Having strong corners is important for any 4-bolt rectangular connection system. They furthermore minimize the need to install clamps, translating in less parts and faster installation times.

Various corner piece types are suited to the various working habits and duct work stability requirements.

1 A-TypeThe original and strongest corner piece. The duct wall seam must be notched out. Available for the 20, 30 and 40 mm profiles.

2 A-Type with Oval HoleSame as above, but with an oval hole for more flexibility during the assem-bly. The duct wall seam must be notched out. Available for the 20 mm profiles only.

3 A-Type with Short LegsWith shorter legs fitting small rectangular duct sizes. The duct wall seam must be notched out. Available for the 20 mm profiles only.

4 S-TypeThe duct wall seam does not need to be notched out. Although ≈ 30% weaker than the A-corners, these are heavy-duty press-formed parts which are stronger than most corner pieces in the market. Available for the 20, 30 and the 40 mm profiles.

5 S-Type with Short LegsSame as above but with shorter legs fitting small rectangular duct sizes. The duct wall seam does not need to be notched out. Available for the 20 mm profiles only.

6 B-TypeMore economical corner piece. The duct wall seam does not need to be notched out. About 40% less sturdy than the A-corners. Available for the 20 and 30 mm profiles.

7 D-TypeMost economical corner piece. The duct wall seam must be notched out. Available for the 20 mm profiles only.

Profile and corner piece dimensions: see additional information ZI-501


G-Clamp

This clamp is based on the proven principle which presses the profiles together using a bolt. This results in a flexible and easy installation.

Because of its solid construction, the G-Clamp is designed to cope with high loads. The clamp bolt is always the same size as the corresponding flange bolts, so that installation can be carried out using the same wrench size.

Installation:Hook the G-Clamp over the profile bead and tighten the bolt. Avoid over-tightening the bolt, since this could deform either the profile or the clamp.

Drive Clamp

This clamp is ideal for situations where installation space is restricted, such as ducts close to ceilings, walls, or other ducts or equipment. The clamp is slightly tapered to ease its installation. Such a clamp is therefore much easier to put in place than the C-shaped long clips.

Thanks to its broad end-face, the drive clamp can be easily driven into position in confined areas using a piece of pipe for instance.

Installation:The flanges must be forced together either by tightening the corners or by using pliers, grips or other suitable tools before fitting the Drive Clamp.

On flanges using type S or type B corner pieces, the clamp can be fitted after bolting the corners together. On flanges using A type corners, the drive clamp must be fitted before the corners are bolted together.

Clamps



The profile´s load-bearing capacity and stability against deflection depend on the operating pressure and the width of the duct. The recommended dimensions are maximum duct widths (DW = maximum duct width).

International norms require that a flange profile under operating pressure should not deflect more than the 250th part of the total duct width (Example: the allowed deflection of a 1000 mm wide duct would be 4 mm). The figures provided on the table below take this requirement into consideration. Prerequisites are sufficiently stiffened duct walls with adequate sheet metal thickness according to DIN EN 12236, April 2002, and the recommended use of clamps as described under „Clamping Recommendations“ in this section of the catalog. The operating range of the rectangular flanges can be increased through the installation of tie rods near the flanges. The reference “with tie rod” means that a tie rod must be installed close to the flange (the distance from the flange must not exceed 50 mm or 1,95 in).

Profile Choices According to Stability (the imperial figures are approximations)

Important: The above recommendations are based on tests which have been conducted on test duct work according to the norms. Other duct constructions, insufficiently stiffened duct walls, different sheet metal thickness, bad quality lock seams, and so on, may have nega-tive effects on the stability of the air duct. The execution of the duct construction according to the above recommendations constitutes therefore no guarantee for sufficient duct stability and does not take away the responsibility from the duct work manufacturer to conduct his own tests. Special conditions such as pulsating air, sudden pressure changes, vibrations, man loads, damaged duct, etc. have not been taken into consideration. In such cases the duct work should be manufactured and tested according to these requirements.

M2-0,6 700 - 500 - - - - - - - - - - - - -

500 Pa without tie rods 500 Pa with tie rods 1000 Pa without tie rods 1000 Pa with tie rods 1500 Pa without tie rods 1500 Pa with tie rods 2000 Pa without tie rods 2000 Pa with tie rods 2500 Pa without tie rods 2500 Pa with tie rods 3000 Pa without tie rods 3000 Pa with tie rods 3500 Pa without tie bars 3500 Pa with tie bars 4000 Pa without tie rods 4000 Pa with tie rods

M2-0,7 1000 - 800 - 700 - 600 - 600 - 600 - - - - -

M2-0,9 1200 1400 1000 1200 900 1200 800 1200 800 1200 700 1100 600 1000 500 1000

M3-0,7 1300 2000 1100 1500 1100 1500 1000 1400 900 1400 800 1300 700 1200 500 1000

M3-0,9 1600 2500 1400 1800 1300 1800 1200 1700 1000 1600 900 1500 800 1400 600 1200

M3-1,2 2000 3500 1600 2500 1500 2400 1400 2200 1200 2000 1100 1900 1000 1800 800 1600

M4-1,2 2500 4000 2000 3500 1800 3200 1600 2800 1400 2500 1300 2400 1200 2200 1000 2000

M4-1,5 3000 5000 2500 4000 2200 3600 1800 3400 1600 3000 1500 2800 1400 2600 1200 2400

Max. Operating Pressures(positive or negative in Pa)

Recommended maximum duct widths in mm

M2-Profile (20 mm) M3-Profile (30 mm) M4-Profile (40 mm)

y y

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The following figures are indications only and do not replace the judgment and analysis of the user with respect to the contemplated application. The stability depends on the sheet metal thickness. Profile Type: Second Moment Section Modulus (in center of area) (in center of area)

Ixs Iys Wxs Wys

M2-0,6-Profile (with A) 0,300 cm4 0,300 cm4 0,200 cm3 0,200 cm3

M2-0,6-Profile Small (w/o A*) 0,200 cm4 0,200 cm4 0,100 cm3 0,200 cm3


M2-0,7-Profile Small (w/o A*) 0,220 cm4 0,281 cm4 0,155 cm3 0,217 cm3



M4-1,2-Profile (w/o A) 2,416 cm4 3,676 cm4 0,915 cm3 1,433 cm3

Profile Form (with A) Profile Form (without A)

METU-SYSTEM Profile Flectional Strength

DWMax. deflection = 1/250 of the DW

* Approximative values as they have been calculated for profiles with A.



Profile Choice depending on the Air-tightness Requirements

Most of the METU-SYSTEM profiles are also available with injected sealant (hd). The profile choice according to the air-tightness requirements is therefore independent from the profile choice based on stability requirements. When using hd profiles leakage is practically eliminated, thus allowing the total duct work leakage to be reduced by 30 to 50% at very little additional cost.

Recommendations for the Ductwork Manufacture According to DIN EN 1507

Class Aa) Flanges can be made with METU-SYSTEM profiles without injected sealant. The corner area of the flange however has to be carried out with care.b) Seams should also be folded precisely if no additional sealant is to be applied.c) During assembly extra care should be brought to properly cover the exposed edge of the duct in the corner area with gasket.

Class Ba) Flanges should be made with METU-SYSTEM profiles with injected sealant (with “hd”). The corner pieces have to be sealed with mastic.b) The seams on ducts with duct edges above 500 mm have to be of high quality. We recommend to apply mastic on snap lock seams. The seams on ducts with duct edges below 500 mm should also be all sealed with mastic, as their number per m2 of duct is larger. The easiest way to do this is to apply the mastic inside the ducts right after their manufacture. c) During assembly we recommend applying two layers of gasket in the corner piece areas. This is especially important if you use S type corner pieces.

Class Ca) Flanges have to be made with METU-SYSTEM profiles with injected sealant (with “hd”). After installing the flange onto the duct, the corner area has to be sealed with mastic.b) All seams have to be sealed carefully with mastic. The easiest way to do this is to apply the mastic inside the ducts right after their manufacture. c) Two gasket layers and/or mastic should be applied in the corner piece area. You should make sure that the gasket layers are placed adequately on the exposed edge of the duct which is not covered by the profile.

Class Da) This air-tightness class can only be achieved through proper workmanship and careful installation practices.b) In addition to the caulking measures required for the air-tightness class C, a mastic sealant can be applied along the entire length of the flange without requiring an hd profile version. In this regard, we strongly suggest that you conduct your own air-tightness tests, as this is the only way to determine precisely which sealing measures are sufficient. This is especially important if the installation is done by a third party.c) The assembly must be carried out with the greatest care. Mastic sealants (applied on the face of the profiles) usually bring better results than the more common self-adhesive foam gaskets bands. Special caution is necessary in the corner piece areas. Also very important is to select large and sturdy enough profiles and corners in order to guarantee that enough compression is exerted on the gaskets and/or mastic at all points of the connection.

For all duct work designed for operating pressures above 1000 Pa, METU-SYSTEM hd profiles should be used.

Important: The recommendations above are based upon our 30 years experience in duct work manufacturing (prior to 1987). However, no liability is accepted for the information provided above. Please keep in mind that leakage is the sum of many smaller leaks. In order to achieve the requirements it is therefore important to respect all the relevant points described above. A bad installation can make an airtight ductwork leak, but a very careful installation can not make bad ductwork airtight!

Sealing the corner area with mastic

Gasket fitted flush to the inner edge of the flange, covering the duct´s exposed edge

The DE Corner Gasket provides a secure and very easy-to-apply seal



1. Cutting the Profiles to LengthThe profile length depends on the type of corner piece used:A and D corner piece types: inner duct length minus 4 mmS and B corner piece types: inner duct length minus 30 mmMost circular saws are suitable to cut the profiles. Make sure to clamp the pro-file on both sides of the saw blade over as much surface as possible in order to restrict any movements. This will protect the sawing blade and your ears! If possible, clamp the profile section in the position as illustrated and note the direction of rotation of the sawing blade. This will ensure that the burrs remain in the inaccessible spots of the flange.

2. Frame AssemblyAssemble the frames vertically, and not horizontally.a) Insert two corner pieces in the ends of both longer profile sections.b) Insert the two shorter profile sections on the corners of one of the profiles.c) Insert the second longer profile with its corners into the shorter profiles.The corner pieces are designed to fit closely into the profile inner shape. A rubber mallet might therefore be necessary to insert them into the profile ends.

3. Frame SeatingStart at one of the upper corners and hammer along the line of the duct (not at the outer edge of the profile). To enable the profile to fit more easily hold it in a slightly inclined position. We recommend to fit the flanges with the duct in a horizontal position. Fit the flanges to both duct ends before fixing. Work on a table or any other flat surface allowing the duct to align itself. To avoid distortion, particularly on small ducts, check if the flanges are aligned on both ends before fixing. On ducts less than 1500 mm long, the flanges can be fitted in the vertical position.

4. Fixing the FrameIt is essential that the flange is securely fixed at the corners (i.e. spot-welding, stitching or blind rivets), where the maximum strength is required. There should be two fixing points with a maximum distance of 20 to 30 mm from each other and as close as possible to the ends of the profile sections. It is also very important that the flange is fully seated against the edge of the duct before fixing. Suitable fixing methods are spot welding, pressure jointing or blind rivet-ing. As soon as the corners have been securely fixed, each length of profile is fixed at a spacing between 80 mm (M2 and M3 profiles) and 120 mm (M4 profiles). For profiles exceeding 600 mm a center fixing is required. Make sure that the flange is fully seated and check the duct alignment before fastening.

5. Sealing of the CornersThe sealing of the corners is important as they can often be a source of leakage. Due to irregularities in the length of the duct walls (i.e. offset seams), a gap can easily be formed which cannot be bridged by the duct´s sealing gasket. Injecting mastic sealant into the pockets of the corner can prevent this leakage risk. The corner pocket should be filled flush with sealant to the face of the flange and over the edge of the duct.

Installation Instructions



Clamping Recommendations (only for products made of galvanized steel)

Straight duct to straight duct connections

Straight duct to fitting connections, Fitting to fitting connections

Explanations: In this case an optimal flange support is reached, since the duct walls run vertically on both sides into the profile. Fewer clamps are required for that reason.

straight duct

straight duct

Explanation: Angled or bent duct walls do not provide an optimal support to the flange. In these cases (please refer to the examples below) more clamps are required.

DW

DW

Important information: The above recommendations are not applicable to flexible joints, since support from the duct wall is lacking. The duct work manufacturer should therefore determine the number of clamps required according to the kind of flexible joint used.

The above recommendations are based on tests which have been conducted on test duct work according to the norms DIN EN 1507. Other duct constructions, insufficiently stiff-ened duct walls, different sheet metal thickness, bad quality locks and so on may have negative effects on the duct work stability. The execution of the duct construction according to the above recommendations constitutes therefore no guarantee for sufficient duct stability and does not take away the responsibility from the duct work manufacturer to conduct his own tests. Special conditions such as pulsating air, sudden pressure changes, vibrations, man loads, damaged duct, etc. have not been taken into consideration. In such cases the duct work should be manufactured and tested according to these requirements.

The information above are only valid with the A and S type corner pieces.

Straight duct

Straight duct

Elbow (outer bow)

Elbow(inner bow)

Straight duct

Reducer

Reducer

Elbow

DW: duct width

DW: duct width

Clamps required for the following duct widths:

OperatingPressures

up to 1000 Paabove 1000 Pa

M2-0,6-Profile

from 1000 mm from 800 mm

20 mm Profiles

M2-0,7-ProfileM2-0,9-Profilefrom 1200 mm from 1000 mm

M3-0,7-Profile


M3-0,8-Profile




30 mm Profiles 40 mm Profiles


OperatingPressures

up to 1000 Paabove 1000 Pa

Clamps required for the following duct widths:

M2-0,6-Profile


20 mm Profiles


M3-0,7-Profile


M3-0,8-Profile




30 mm Profiles 40 mm Profiles


• Two-part corner pieces designed for ductwork with

formed-on flanges (i.e.FIRMAC duct lines).

• The patented corner design guarantees a 90° angle and

maximum stability.

• Fast and easy installation: a hammer is all that is needed!

• A special stop secures the corners into the flange.

Shape of the corner pieces outside the profile

Shape of the corner pieces inside the profile

The Flat Part Corner Piece is kept into position by a large groove, thus ensuring a 90° angle

The thick material increases the corner‘s stability in order to resist the bending loads generated by the corner bolts.

Both corner pieces fit perfectly flat together. This increases their

stability

Flat part of the corner piece

Formed part of the corner piece

Formed part of the corner piece

Flat part of the corner piece

Corners for Formed-on Flanges

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The M2-Z and M3-Z corner pieces consist of a formed-part ...

Installation Instructions

M2-Z-Corners (for 20 mm formed-on profiles)Art. No. Description A02A-2003 M2-Z-Corner, galv., Flat Part A02A-2004 M2-Z-Corner, galv., Formed Part

M3-Z-Corners (for 30 mm formed-on profiles)Art. No. Description A02A-3003 M3-Z-Corner, galv., Flat Part A02A-3004 M3-Z-Corner, galv., Formed Part

Designation

Formed Part A B C D E F

M2-Z-Corner 70,0 5,2 9,2 9,0 18,0 2,0

M3-Z-Corner 100,0 7,5 14,0 12,0 27,0 2,5

Flat Part A B C D E F

M2-Z-Corner 70,0 1,5 3,0 9,0 18,0 2,0

M3-Z-Corner 100,0 2,5 4,0 12,0 27,0 2,5

Dimensions (mm)

... and a flat-part

Hammer the formed part inside the profile

Then insert the flat-part in the U-shaped groove of the formed-part

Then hammer the flat-part all the way down.

Finally, secure the corner piece in place by hammering

down the stop

Corners for Formed-on Flanges

Rectangular Duct Connections - METU Meinig AG Catalog 6b 9 Rectangular Duct Connections M2 M3 M4...

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