Accessories And Auxiliary Equipment

The dry running protection units (STP2A, STP2D) continually monitor the surface temperature of the stator during operation. Should the operating temperature rise over a predetermined set point due to an increase in friction caused by dry running, a signal is sent to the motor control unit and the pump shuts down. This prevents any damage to stator and rotor. The controller can be set for two different switch-off temperatures: the first set temperature would be for the normally pumped product, the second set temperature for a different substance temperature, for example during a cleaning process.

The flow sensing unit is used to protect a pump fitted with a solid stator against dry running. The unit is installed in close proximity to the pump itself, either in the suction or in the discharge pipework. Should the flow drop below a certain level, indicating a dry running situation, a signal is sent to the motor control unit and the pump shuts down, thus preventing any damage.

Some processes require that the rotational speed of the pump be monitored. Where this is necessary, NETZSCH offers impulse switches mounted to the drive unit. The shaft can be fitted with one or more contacts to measure the required number of impulses per revolution. These units can be fitted to both block construction and bearing housing pump designs and are supplied securely mounted to the lantern or the bearing block.

The operating pressure is displayed by means of a pressure gauge. This gauge is isolated from the process fluid by a stainless steel diaphragm. The G3/4 inch gauge is suitable for use with substances of low to medium viscosity. The pump shuts down automatically when the maximum allowable pressure is exceeded; this cut-out pressure is adjustable.

This pressure gauge differs from the G3/4 inch by means of the DN50 open measuring flange. The large nominal width of the measuring flange enables dependable protection against overpressure even for highly viscous and clogging substances.

The operating pressure is displayed by a Bourdon gauge which is securely isolated from the process fluid by means of an elastic diaphragm. The pump shuts down automatically when the maximum allowable pressure is exceeded; this cut-out pressure is adjustable. The Pressure Control Device is also optionally available with a differential pressure on/off switch.

In addition to a display indicating the current operating pressure of the pump, this easy-to-install unit also allows the setting of additional points for alarm or emergency shut-down due to overpressure.

Dry running of the shaft sealing ring can be securely prevented if the quench pot of a shaft seal operated with quench is permanently flushed with fluids. The installation of a quench pot can also prevent the pumped product from crystallizing due to contact with the atmosphere.

The Permanent Lubricator is used to support the sealing function of the shaft seal. It can be used for packed glands as well as mechanical seals fitted with an additional quench ring. The function of the Permanent Lubricator is to continually keep grease in the grease chamber ring or quench pot under pressure by means of a pre-stressed spring. A shut-off device on the lubricator can be activated to accommodate periods when the pump is idle.