MU Instructions

To control the inner duct-Ø please refer to the MRD measuring band instructions. In case of deviations beyond the tolerances, read the values on the scale and send us that information when placing your order. 

The MU can bridge Ø differences up to 4 mm. They are therefore well suited for the connection of straight ducts and fittings.

When correctly installed the highest air-tightness class D (DIN EN 12237) is achieved.


To achieve an even higher air-tightness, apply some sealant on both sides of the duct seam on the area where the MU will be mounted. For liquid and oil-tight connections please refer to the METU-FORM system of ducts, fittings and connections.

Push the duct ends into the MU Overcollar so that there is only a narrow gab or even no space between the duct ends. Both duct ends should enter equally deep into the MU Overcollar.

Tighten the M6 hexagonal socket head screw (or "Allen bolt") and apply a maximum torque of 5 Nm. For MU Overcollars in stainless steel use a stainless steel lubricating, anti-seize compound and tighten the Allen bolt slowly per hand.

The METU round duct connections have been designed to assemble the ducts together, but not to support additional static loads or to serve as suspension attachments. The duct suspension must therefore be planned independently without subjecting the round duct connections to additional loads.When installed vertically, each duct segment must be individually fixed and secured.

MU Overcollars Installation Video