The dry running protection units (STP2A, STP2D, STP3) continuously monitor the surface temperature of the stator during operation. If the operating temperature rises 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 temperature can be set 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. If flow drops below a certain level, indicating a dry running condition, a signal is sent to the motor control unit and the pump shuts down, thus preventing any damage.
Some processes require monitoring of the rotational speed of the pump. When this is necessary, NETZSCH can supply 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 pedestal or the bearing block.
A pressure gauge which is isolated from the process fluid by a stainless steel diaphragm is available. The G 3/4-inch gauge is designed for use with substances with low to medium viscosity. This gauge can be combined with a switch to automatically shut off the pump when the maximum allowable pressure is exceeded; this cut-out pressure is adjustable.
The operating pressure is displayed by a Bourdon gauge that 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 can be supplied with a differential pressure on/off switch.
The Permanent Lubricator supports 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 Permanent Lubricator keeps 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.
Back-to-back mechanical seals require a sealing water supply unit for correct operation and the sealing pressure must be must be at least 29 psi / 2 bar above the prevailing pressure in the suction housing. A pressure and flow monitoring system is mounted onto the pump to control the volume of flow in the seal chamber.
When conveying high viscosity media, we recommend you install a ring dosing nozzle to reduce pressure loss in the pipeline. This nozzle fits directly behind the pressure joint of the pump and, depending on the lubricant introduced through the nozzle, the discharge pressure can be reduced by up to 70% as a result of frictional loss. This option can significantly lower investment and operating costs.
To protect floor surfaces, machine feet can be mounted directly to the baseplate for pump installation. Flooring is not damaged as it would be with an anchor bolt system. After installation, there are no crevices or hollows for the accumulation of bacteria and the floor is more easily accessed for cleaning. The stainless steel threaded spindle of each foot adjusts to irregularities in the floor surface.