Dosing diaphragm pumps НДР-2М

Dosing diaphragm pumps series NDR-2M, produced at the Kharkov Pumping Plant, designed for pumping liquids and suspensions, including toxic and aggressive. The presence in the pumped liquid abrasive is not a problem for the diaphragm pump. Pumps are modular. The main components: drive, coupling, electric motor, hydraulic part. The drive is specially designed for use as part of a diaphragm pump, but can also be used with classic plunger hydraulics. Plunger stroke length adjustment system which the drive is equipped, allows to carry out smooth adjustment of giving from zero to nominal rate. Adjustment is possible, both when the pump is stopped and on the go.

Hydraulic part

Independent module. It consists of a reservoir for hydraulic (working) fluid, a diaphragm actuator housing, a plunger seal, a diaphragm assembly and a valve box. The sealing of the plunger does not require maintenance during operation. The membrane assembly is a two-layer membrane of specially treated PTFE, and a device for returning the membrane to its initial position. Membrane, hydraulically loaded with pre-mechanical tension. The device to return the membrane to its initial position by creating a pre-tension significantly increases the suction capacity of the pump: the pump can operate at a pressure on the suction nozzle close to the vapor pressure of the pumped liquid. A rigid seal in the center of the membrane ensures its precise centering, and thus, a long service life. The two-layer membrane design allows, in case of a break of one of the layers, to continue the safe operation of the pump without changing its parameters for some time needed to prepare for stopping and replacing the damaged part. It is possible to signal if one of the membrane layers is damaged. The hydraulic part is equipped with a built-in safety valve. Its purpose is to protect the pump from overload with an unacceptably large increase in pressure in the pressure line up to its complete overlap. Membrane dosing pumps NDR-2M were developed to replace the classic plunger pumps that are used in technological processes where leakage of the pumped medium is unacceptable. It is known that the plunger seal in classic pumps works reliably, provided it is constantly lubricated. Lubrication can be achieved in two ways:

• supply to the sealing area of a special barrier fluid under pressure exceeding the operating pressure of the pump;
• organization through the seal of the normalized (drip) leakage of the pumped liquid.

Both methods are associated with the complication of pump maintenance, the need for constant monitoring, tightening and replacing the seal. In addition, in the first case there is leakage of the lubricating fluid to the outside, in the second case – the pumped.

A distinctive feature and the main advantage of diaphragm pumps is the complete tightness of the pumped liquid in relation to the environment. The seal in this pump does not require maintenance during operation.

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