SPECIFICATION 

 Horizontal thrust restraints shall protect air handlers against excessive displacement resulting from high air thrusts comparing with the equipment weight. This restraints consist of a spring element in series with a neoprene pad as described in specification with the same deflection as of the spring isolators and isolation hangers as specified. The spring element is designed for factory preset and field adjustment for thrust to allow a maximum ¼”(6mm) movement at start-up and shut-down. The assembly furnishes with one rod and angle brackets for attachment. The unit shall be installed at the centerline of thrust and symmetrically on both side of the equipment. UNISON Engineering Co., Ltd. Manufactures type HTR for this thrust.

 HORIZONTAL THRUST RESTRAINTS

A very high air thrust comparing with weight ratio for isolating equipment offers us the problems quite often and we should not expect the mountings alone handle this thrust by simply adding some mass to the system to stiffen the spring-which is not practical. The air thrust may happen to all the equipment whether is hung of floor mounted. So we have designed a horizontal thrust restraint by modifying spring hanger adjusted with precompression still limit movement when the system starts-up and shuts-down and the air pressure builds up or dies off.

We can use this device in connection with spring isolators or spring hangers.

DESIGN CONDITION

As a cabinet containing a fan and motor and no accessories such as coils or filters fan heads may develop extremely high thrusts which are equal to the suction are multiplied by the negative head plus the positive pressure multiplied by the discharge area. These forces act horizontally, apposite to the air flow they tend to shift and overturn with damage to the flexible connections or the unit themselves.
Thrust restraints are recommended for all fan heads and for axial or centrifugal fans when the air thrust exceeds 10% of the equipment weight.