Friday, February 15, 2008

Trial Instrumentation Field Device ECP Flow Switch Chlorine Application Failed

Again, this morning operation raised defect to us on Electro Chlorination Plant (ECP) flow switch problem. After a few days switch has been installed with minor modification on the probe; new spring changed to stainless steel and the flapper is coated with anti-oxide hoping that the lifetime can be longer than before, but the result frustrated. There is already a few times I mentioned in this blog that the unreliable flow switch urgently needs to be replaced as the ECP Cell downtime very frequently happened.

Recently, Vega and Endress Hauser tested their probes on the ultrasonic type. It took one week to complete in January. The tuning of the parameters has been done for a few times to get a good result but at the last stage it failed. The reason it failed is the flow rate is not stable due to two medium mixture, water and air bubbles. In this case, air bubbles will absorb the signal from the ultrasonic then cause the reading fluctuating. At the end, they would like to trial another type of measurement either magnetic or different pressure DP type. But I am still waiting for them to their recommendation which has been promised in February.

I still remember that the current Flotech flow switch that we are using already more than two years. But recently in these 3 to 4 months, the flow switch flapper and the spring brittles and easily broken. Actually this is not the first time we change to a new brand on ECP flow switch. If I am not mistaken, it is already third or fourth times since 2004. So far most of our instrumentation field devices when comes to a new solution doesn’t give us much trouble. Aaarrrgghh… meaning that I have to find out other new brand or new type of flow switch to cut this problem from happens and happens again.

At this moment, I have to contact various manufacturers to recommend the suitable flow switch on the chlorine application which urgently required including ABB, UE and Kelco. Since the stocks balances at the store for the old type (Flotech) are very critical low therefore we need to reorder for temporary used.

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