Polyethylene (PE)

Our conductive versions are available for all ATEX zones – even zone 0 is possible. The pump does not lose any of its technical features and can thus be used without limit in productions in which increased fire and explosion risks prevail. Our team will be happy to advise you, according to the area of application and requirements, in the selection of the right double diaphragm pump.

A contactless sensor (proximity sensor) is installed in the motor housing. This registers every second stroke of the diaphragm in the pump chamber. This type of stroke counting is independent from the operation mode of the pump. The signals from the sensor can, for example, be transmitted to an available control unit or an optionally available stroke counter. The strokes for the pump can be pre-defined via the stroke counter.

Once the preset stroke rate is reached, the pump is switched off using a likewise optionally available solenoid valve. The strokes can also be captured pneumatically using a pressure sensor. Here, the pressure change in the motor housing is measured behind a diaphragm.

Stroke counters are available in the following models:
SC 1 – Proximity sensor (Namur) with approx. 3.0 m connection cable
SC 2 – Proximity sensor (Namur) with stroke counter
SC 3 – Proximity sensor (Namur) with stroke counter and intrinsically safe isolating amplifier in accordance with potentially explosive areas
SC 5 – Pressure switch (1.0 – 10.0 bar) with approx. 5.0 m connection cable
SC 6 – Pressure switch (1.0 – 10.0 bar) with stroke counter

Note:
If the proximity sensor (SC 1) is used in a potentially explosive area, an intrinsically safe isolating
amplifier should also be provided.

The buffer chamber system with diaphragm monitoring is available in the following models:
BC 1 – Buffer chamber system with diaphragm monitoring, with sensors
BC 2 – Buffer chamber system with diaphragm monitoring, with sensors and switching device
BC 3 – Buffer chamber system with diaphragm monitoring, with sensors, switching device
and an intrinsically safe isolating amplifier (potentially explosive areas)

Note:
The maximum permissible operating temperature for pumps with buffer chamber system with diaphragm monitoring is +70 °C for PE pumps and +80 °C for PTFE pumps.

For pumps with side housing made from plastic (PE and PTFE, also electrically conductive), the backwash system allows for the removal of residues from pipes and pumps. A bypass line is introduced into the side housing for the pump. The bypass line is opened via manual valves. Care should be taken to ensure that the manual valve is turned by max. 10 mm since the lift on manual valves is not limited. The bypass line can also be opened using pneumatically operated valves.

For this, a valve control pressure of at least 3.0 bar is required. For pumps with side housing made from metal (aluminium, grey cast iron and stainless steel), the backwash system allows for the removal of residues from pipes and pumps. To do this, the ball valves in the pump chamber are manually lifted on the draw and pressure sides. The backwash system/ball valve raising can automatically be activated when the pump is switched off if an optionally available 4/2-way valve is used.

The backwash system/ball valve raising is available in the following models:
BF 1 – Backwash system with manual valve, EPDM seals for pump housings made from plastic and metal
BF 2 – Backwash system with manual valve, PTFE seals for pump housings made from plastic and metal
BF 3 – Backwash system with manual valve, FPM seals for pump housings made from plastic and metal
BF 4 – Backwash system with pneumatic valve, EPDM seals for pump housings made from plastic
BF 5 – Backwash system with pneumatic valve, PTFE seals for pump housings made from plastic

A moisture sensor (capacitive) is installed in the pump’s silencer. This sensor detects any liquid which inevitably gets into the pump motor in the event of a diaphragm rupture. The sensor’s output signal can be transmitted to an available programmable memory controller or an optionally available control unit.

If the sensor transmits an alarm signal, this alarm can be transmitted to a likewise optionally available solenoid valve. The solenoid valve shuts of the air supply. The pump stops.

Note:
If the pump is operated with an upstream moisture separator (filter regulator), damp compressed air can lead to triggering of the sensor (alarm). It is therefore mandatory to install an optionally available moisture separator (filter regulator) before the pump.
If diaphragm monitoring (DM1, DM2) is used in a potentially explosive area, an intrinsically safe isolating amplifier should also be provided in addition to the proximity sensor.

Diaphragm monitoring is available in the following models:
DM 1 – Moisture sensor, capacitive (Namur) with approx. 3.0 m connection cable
DM 2 – Moisture sensor, capacitive (Namur) with control unit

When operating compressed air driven double diaphragm pumps (positive displacement pumps), a pulsating delivery flow results from the oscillating movement of the diaphragm. In order to achieve an almost uniform delivery flow, the use of a suitable active pulsation damper is mandatory.

The Dellmeco F range is a specially developed pump with integrated pulsation damper and two separate product chambers. The first product chamber is used for delivering a liquid from a reservoir to the system. This chamber works by using a directly installed and actively controlled pulsation damper. The product flow is thus delivered evenly. An air pressure of at least 1 bar is required for perfect use of the pulsation damper.

The second chamber is used for returning the excess product (e.g. colour, glue, adhesive, etc.) from the system to the reservoir. The second chamber can also be used for circulating the product in the reservoir. The quick sedimentation of a product can thereby be prevented.

When using Dellmeco pumps with plastic housing, the pulsation damper is screwed directly onto the material outlet without the use of further components. When using pumps with metallic housing, the pulsation damper is installed downstream from the pump. Each pulsation damper has a separate compressed air connection. Pumps and pulsation dampers should be connected to the compressed air supply together so that both units are supplied with the same air pressure. As soon as the pump is supplied with air pressure and begins delivery, the pulsation also begins reducing the pulsation. The diaphragm in the pulsation damper, as in the double diaphragm pumps, serves as a separating membrane between the air side and the product side. If the air pressure is reduced or increased as a result of modified operating conditions, the pressure on the delivery side is also reduced or increased. This occurs both in the pump and in the pulsation damper. Consistently good damping of the pulsation is achieved, caused by this automatic adjustment of the pressure.
Use in potentially explosive areas (EX II 2GD TX) is assured through the use of conductive polyethylene as the housing material.