Devices on the doors of a purged panel

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wireman

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Could I put a 24vdc powered HMI and 24vdc powered pilot lights on the door of a purged control panel if the power to these devices go through intrinsic barriers (also located in the enclosure)?

This would be in a Class 1 Div 2 (gases) area. The purge system would be a Type Z, which reduces the classification of the enclosure from Div 2 to non-hazardous.

The other hitch is the only power will be a battery inside the enclosure. The purged system can shut off the power leaving the battery but of course there would still be power available across the battery's + and - terminals. So technically I guess you could say not all of the power is disconnected inside the panel when it is not purged.

Any thoughts?
 
wireman said:
Could I put a 24vdc powered HMI and 24vdc powered pilot lights on the door of a purged control panel if the power to these devices go through intrinsic barriers (also located in the enclosure)?

This would be in a Class 1 Div 2 (gases) area. The purge system would be a Type Z, which reduces the classification of the enclosure from Div 2 to non-hazardous.

The other hitch is the only power will be a battery inside the enclosure. The purged system can shut off the power leaving the battery but of course there would still be power available across the battery's + and - terminals. So technically I guess you could say not all of the power is disconnected inside the panel when it is not purged.

Any thoughts?
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Why not just buy an HMI that is already rated for C1D2? Many of them already are. many off the shelf HMIs are not suitable for use in a purged area as the membrane keypad and/or touchscreen overlay can separate from the internal pressure.

I am not sure the lights are an issue. You can buy them rated for C1D2 as well.

Normally a type Z purge system will not have any means to automatically shut off power.
 
petersonra said:
Why not just buy an HMI that is already rated for C1D2? Many of them already are. many off the shelf HMIs are not suitable for use in a purged area as the membrane keypad and/or touchscreen overlay can separate from the internal pressure.

I am not sure the lights are an issue. You can buy them rated for C1D2 as well.

Normally a type Z purge system will not have any means to automatically shut off power.
Click to expand...

Bob,
Thanks for your reply. A C1D2 rated HMI is certainly an option. What I haven't had time to look at yet is if one is available in a model similar to what else is used in the plant.
I'll look into the pilot lights.

As far as shutting off the power, from what I've read in P&F's literature about C1D2 Type Z systems: "power can be deactivated or an alarm must indicate a loss of pressure." Since the cart is portable they won't want to be dragging around a cable to attached to an alarm located somewhere else. Figured it would easy enough to just shut off the power.
 
Not sure the alarm would have to be remote. A local alarm on the cart would work if the area is occupied.
Otherwise a monitored wireless alarm connection should work, yes?

Tapatalk!
 
GoldDigger said:
Not sure the alarm would have to be remote. A local alarm on the cart would work if the area is occupied.
Otherwise a monitored wireless alarm connection should work, yes?

Tapatalk!
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maybe the rules have changed but the last time I did one of these no alarm was required at all. just indication.
 
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