General information
15
SAFETY PRESSURE SWITCH
It is set at a pressure higher than the maximum one of the regulation pressure switch, but always lower than safety valve opening
value.
The safety pressure switch is triggered in case of regulation pressure switch fault and permanently stops the burner.
The burner will be switched on again only after the water pressure value has decreased and the control panel has been manually
reset.
The calibration of this pressure switch is carried out with a procedure similar to that used for the regulation pressure switch, with
the only requirement of setting the drum indicator to 1, practically with a zero differential.
2
1
5
6
4
4
3
1
Sealed anti-tampering cap
2
Polyamide cover
3
Stainless steel bellows
4
Pressure connection G 1/2 A
5
Protection class IP 66
6
2 x PG 13.5 cable diameter 6 - 14 mm
7
SPDT interchangeable contact system
m
IMPORTANT
The safety pressure switch is calibrated and sealed during generator construction.
Operation
When the pressure exceeds the set value, contacts 1-4 close and contacts 1-2 open. Contacts go back to their initial position when
the pressure drops below the set value, minus the differential value (fixed at 1.2 bar).
I
II
1
4
2
IS
D
M
1
4
2
1
4
2
I
Alarm triggered by the increase of the pressure above the set value.
II
Alarm triggered by the decrease of the pressure below the set value, minus the differential value.
IS
Scale setting.
DM
Mechanical differential.
Intrinsic safety operation for increasing pressure
The figure shows a section of the intrinsic safety bellows for increasing pressure.
When pressure increases, the contact lever interrupts the connection between
terminals 1 and 2. Should the internal bellows pierce, the pressure will be sent to the
external bellows.
The external bellows surface is three times higher than the one of the internal bellows.
The connection between terminals 1 and 2 is interrupted. Should the external bellows
pierce, atmospheric pressure will be present between the two bellows.
The contact system interrupts the connection between terminals 1 and 2. Thanks
to the double bellows structure, in case of breakage, fluid will not leak into the
environment.
Cooke Industries - Phone: +64 9 579 2185 Email: [email protected] Web: www.cookeindustries.co.nz
