Polyethylen (PE) ist sehr robust und äußerst beständig gegen Abrasion. Das Material nimmt sehr wenig Feuchtigkeit auf und überzeugt durch eine hohe Beständigkeit bei vielen Chemikalien (nicht beständig bei Salpetersäure, rauchender Schwefelsäure sowie Halogenen). PE weist eine ca. 7-fach höhere Abrasionsfestigkeit gegenüber PP auf. Selbst gegenüber Stahl ist diese noch um das ca. 1,6-fache höher. Die Gebrauchstemperatur liegt bei ca. +90°C. Eine wesentliche Rolle spielt diese Abrasions-festigkeit bei Beizbädern in der Galvanik, Druckfarben, Kalkmilchförderung, Keramikmassen und bei Glasuren.
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
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.
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 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.
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