NHM Series
- Overview
- Features & Benefits
- Specifications
- Other Info
Overview
The Dickow NHM Series is a range of sealless, magnetically coupled hot water circulation pumps. It has been developed for medium and large size heating applications which require water temperatures > 180°C. The NHM variant is designed for pressures up to 45 bar @ 238°C with a maximum capacity of 900 m³/h and differential head of 150 m.
The series are single stage, volute casing pumps with a back pull out design, an end suction flange and a centreline discharge flange. In order to take full advantage of the back pull-out design, spacer type couplings are recommended so that the motor can remain bolted to the base plate. The standard pump casing is cast in one piece and foot mounted on the base plate, sealed to the atmosphere by confined non-asbestos gaskets.
Casings with rigid foot mounting are supplied as a standard. Casing bolts are of heat resistant expansion type. For applications with temperature swing, additional cup springs avoid leakage, caused by thermal expansion. Confined gaskets avoid blow-out of the liquid.
Closed impellers are standard. Impellers are cast in one piece with solid hubs. To minimize the axial load of the bearings, the impellers are fitted with wear rings on the back and balance holes to the suction. The impellers are keyed to the pump shaft and secured by cap screws with Heli-Coil-inserts. The replaceable wear rings are held in place by a press fit with locking screws. Additional impeller wear rings are available as an option. The running clearances are in accordance with API 610.
The pump shaft is carried by antifriction bearings outside the pumped liquid. The bearings are oil lubricated with the level regulated by a constant level oiler. The calculated service life of bearings is in excess of 25000 hours.
