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8.1 Pressure tank
Installation of a pressure tank in the hydraulic system is recommended to compensate leakage of water in the
system (or during minimum water demand) and to avoid continuous start/stop cycling of the pump (check the
appendix for more information).
Selecting the proper volume and pre-charge pressure of the tank is very important; smaller tank volumes will not
compensate adequately for minimum water usage or leakage, while larger volumes make it more difficult for CM to
control the pressure evenly.
Recommended tank volume is equal to the 10% of the maximum water flow of the system (expressed in volume
unit/min)
Example:
if the max water flow is 50 liters/min, the pressure tank should have a capacity of 5 liters
If the max water flow is 20 gpm, the pressure tank should have a capacity of 2 gallons
Pre-charge pressure of the pressure tank should be at least 1 bar (15 psi) less than the set-pressure of the system.
Example:
if the set-pressure of the system is 4 bar, the pre-charge pressure of the tank should be 3 bar
If the set-pressure of the system is 60 psi, the pre-charge pressure of the tank should be 45 psi
8.2 Pressure sensor
It is possible to use pressure sensor with a linear output signal with range 4 – 20 mA.
Pressure transducer will be powered by any range of DC voltage including the value 24 V.
It is necessary to set the pressure sensor characteristics in the initial configuration menu or in the installer menu
(please check the relevant chapter on setting parameters).
The connection of the pressure sensor is through the analog input terminals
0V (signal GND, if available)
+24V (power supply 24 V dc)
AN1 (signal 4-20 mA)
CM accepts the signal of an additional pressure transducer to be activated automatically if the first transducer fails;
it is enough to connect the wires of the additional pressure transducer to pin AN2 (signal 4-20 mA) and +24V (power
supply 24 V dc).
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