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Testing methods for float-type liquid level switches

Testing methods for float-type liquid level switches

Testing methods for float-type liquid level switches

(OP)
Hello all,

Was wondering if anyone could share their inspection practices for mechanical float-type liquid level switches.

We have some tanks fitted with a chain that can be used to pull the float up and test the signal, but there are concerns that the mechanical linkage may not go back to the proper position; also concern that if the float itself had a hole or crack, the liquid would fill it up and it wouldn't float.

We have discussed 'wet testing' by removing the entire assembly and floating in a pail of product to ensure it displaces, but that is a pain and safety concerns about doing this on top of a tank.

Primary concern is for liquid petroluem vertical storage tank applications.

Any thoughts / ideas / best practices out there?  Thanks,

RE: Testing methods for float-type liquid level switches

Most companies avoid mounting internal float level switches on a vessel.  If you use a bridle you can block the vessel then vent and fill the bridle to test the increasing level and drain to test the decreasing level.

RE: Testing methods for float-type liquid level switches

Do what JLSeagull said.

Also, considering the very low cost of float switches, put in as many redundant ones as you think you need to feel comfortable -- depending on how critical the process is.  

Good on ya,

Goober Dave

RE: Testing methods for float-type liquid level switches

Please give us the make & model of the switch.
Are you sure it's a float, not a displacer?
Roy

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