VHV - Reciprocating Pumps
With Pre-load Stage

In some cases, for structural reasons, it is not possible to make a suitable tank connection for the operation of single-acting low-temperature pumps (such as the TL, SA or HK types). This especially affects the available net positive suction head (NPSH) value at the level of the piston in the pump when connected to horizontal tanks or tanks near to the ground and when the liquids which are delivered are already boiling due to heat absorption from the outside. The VHV series of pumps with forced push-action cylinder filling was developed with these types of installations in mind.

The medium which enters from below circulates in the pump head due to natural convection and the movement of the piston. During the return stroke of the piston rod, a larger volume of fluid is enclosed by the rear suction piston. As the piston moves towards bottom dead centre, this volume of liquid is propelled, gas-free, into the pressure cylinder through the suction valve integrated in the piston rod. An integrated relief valve prevents over-compression in the pressure cylinder while it is being filled. The medium is discharged via a pressure valve fitted centrally to the front.

The frictional heat being developed by the piston oscillation is withdrawn from the pump head by natural convection via the gas return feed fitted to the top.

The robust, non-wearing pressure-valve construction leads to low maintenance costs and high operating reliability.

VHV pumps can be used both for gas bottling and as process pumps. Ultimate pressures of up to 400 bar are reached in the standard version. VHV pumps are intended for use at temperatures down to -196°C with effective vacuum insulation. Power transmission is achieved via a type DF-01, 60 mm stroke, belt-transmission eccentric drive. VHV pumps are supplied with all accessories mounted on a galvanised steel frame. The twin or three-head pump designs with coupled DF-02 or DF-03 drives can deliver large discharge volumes even at high ultimate pressures.

VHV pumps are available with speed controllers with or without explosion-protection construction for flammable or explosive discharge media.

Click the image for a detailed view!

Design features:

• pressure cylinder filled by forced action from a suction piston, thus also facilitating the delivery of boiling liquid or delivery when the NPSH » 0;
• structural separation of the pump head from the drive prevents any unacceptable contact between lubricant and discharge medium;
• shearring coupling between the pump head and the drive protects the pump against unacceptable mechanical loading;
• the piston-rod seals are heated (vacuum-insulated types only) thus making it possible to stop without having to relieve the pressure and heating the suction side;
• PTFE bellow acts as additional protection for the piston rods against contamination from the outside and moisture from the atmosphere;
• temperature-controlled warning system integrated in the pump head to protect against the unacceptable dispersion of cold due to leaks;
• supervision of flow by means of a flow monitor on the pressure side.
• pulsation damping on the pressure side;
• complete pump control set including automatic start routine (automatic valve control on suction side), stuffing box temperature control and dry running protection.