Instate of giving details about Low cooling water pressure switch (LCWPS) I am giving you details about Low Cooling Water Flow Switch (LCWFS).Why I am
doing this? not to any perticular reason,but the operation & setting of LCWPS is same as LOPS(Low Oil Pressure Switch).Same INDFOS Make-IPS 70 switch
is used as LOPS & LCWPS,the only difference is “LCWPS” used in discharge (outlet) water line of closed circuit system or in water inlet (between inlet valve & compressor) for open drain type system of air compressor.Find the details about LOPS from previous post.
Details about Low Cooling Water Flow Switch:-
Flow switch consist of a microswitch,mounted outside the stream is actuated by a metallic belolow sealed pivoted flapper.A SWITZER Make,Type-CR25MV
is the common switch used as LCWFS.
The Location and Installation of LCWFS:-
Flow switch should preferably be mounted in a horizontal section of cooling water pipe.Where there is a straight horizontal of atleast five pipe diameters on either side of the flow switch.Weld a socket of 1” BSP thread on water inlet line,for free movement of the flapper in pipe without rubbing the side.Open the instrument cover,remove spring hook from the horizontal balancing arm & refix after the instrument is mounted on the pipe.The flapper of LCWFS must be in right angle to the flow & the arrow mark on the body is in same direction of water flow.Check the operation of flow switch to ensure that the flapper is free to move inside the water pipe line.
This is also important safty for your Air Compressor.LCWFS must be in working condition to avoid any breakdown to the compressor.Now know about
operation.
The pressure applied at the sensor creates a force against the balance plate through the operating rod.The upward movement of the balance plate is
countered by a contineously adjustable range spring,which is used for setting pressure values.When the input force overcomes the spring tension,the
balance plate just moves and operates the microswitch.On reduction of the applied pressure of the flow,the microswitch is automatically reset & balance plate is restored to its original position.
How to set the LCWFS in water pipe line.
Indentify the NO & NC contact of the microswitch and check the function of switch by moving flapper to and fro.Fit the Switch in pipe,open water inlet &
outlet valve fully,at this maximum flow Normal Open (NO) contact will close.reduce the water flow to minimum requirment of Air Compressor & rotate
the adjusting range spring, so that the switch is to be set this range as its normal condition i.e.Normal Open contact remain open.Then increase the water
flow to the fair requirment,now this NO (Normal Open) contact must close,if not,adjust the screw.
Check the actual operation of the microswitch by gradually opening & closing the water outlet valve.So that as the water flow falls to the minimum
requirment.The contact must open, and close when the flow reaches fair requirment.
Do not avoid safty switches .It will protect your Air Compressor from breakdown.
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