Overriding a flow switch

Hi there,

Interesting question that will divide a lot of technicians, engineers and operators!
The manual bridging of a switch has some key risks associated that when ineffectively controlled, put the machine and personnel at risk. A few questions to ask yourself before proceeding, which I’ve summarised below.
1) Does this comply with my company inhibits / overrides policy?
2) What does the switch monitor / system installed on?
3) Why is there switch present – what is it protecting the machine from?
4) If I installed the manual bridge, what would be the result if:
– The switch was activated during start-up?
– The bridge was left in and forgetting and the switch was activated during normal operation?
– The switch was removed completely?
5) Is there risk to personnel if the bridge is installed and machine is operated?
6) What is the duration of the bridge?
7) Is there a defined policy to ensure the bridge does not remain installed (if just for a start permissive) or until such a time that the issue is further explored, i.e. Procedure or Implemented WO to remove?

Number of item to consider here that are not always easy to answer. Just for my opinion, we tell our technicians that the switch has been installed for a specific reason, whether to protect the machine from adverse conditions during start-up, operation or periods of instability. The most effective override is a software override, complying with relevant company policies to ensure it is removed. Too many times have overrides been left in place (physical) damaging the machine or impacting personnel. If the switch is causing constant repetitive issues, it is best to explore the underlying root cause (e.g. incorrect switch, other system factor). Production is important, but the health of the machine and safety of your people is paramount – just something to consider. We are here to help! Send us an email of the issue switch in question with some drawings and our Engineering team can advise checks / recommendations.

Hope this helped!