Gas meter pulser wiring

[rootboy]

Hi guys,

As part of our contract, we are installing new natural gas meters with integrated pulsers that give us a pulse every so many cubic feet of gas.

The pulse that we get from the meter will then be used for utility logging.

Internally to the meter the circuitry is an open collector output that will drive itself low when we get a pulse. The source voltage will come from the RTU collector panel. Pretty standard stuff.

The cable going into the meter is connected via a standard appliance crimp-type connector and there is no provision for wiring this using explosion-proof methods.

The question that we have here at the office is: does this meter have to be connected using intrinsically safe methods? The device feeding the sensor is not intrinsically safe, so there is a chance of ignition should the wires going to the meter become shorted.

Personally, I think that it's necessary, for CYA purposes if nothing else (if someone takes out the meter with a fork truck, then the wires to the meter will probably short out and possibly cause an explosion).

The argument against installing this as an intrinsically safe circuit is that we ignore the 800 lb gorilla in the room, that being the electrical service right next to the gas meter.


Thanks for your help,

John

 

[jbelectric777]

As usual I dont have an 08 book handy but it sounds like your meter/s are pulsing ma or mv signals. Check your NEC but more important is check the manufacture information. I really dont think I.S wiring method is needed or required, if it was the units installation would recognize that because your talking about a big amount of money. Wish I could give a definitive yes/no but I wish you luck. Jim

 

[Cmdr_Suds]

Has anyone classified the room as hazardous? If not, then just because you have a natural gas line and meter does not make it so(how many boiler rooms have you seen that are not explosion proof). The meter if properly listed as a gas meter with a pulser output would say if it needed to be installed intriniscally safe. Like you noted, If you have power close by that's not installed in an Explosion proof manner, then your little pulser line would not be required either.

 

[rootboy]

Thanks guys, the meter manufactuer recommends I.S. wiring, and just from a CYA perspective, I would concur.

But as Cmdr_Suds points out, it's unlikely that anything else in the area is explosion-proof.

As for the manufactuer of the other end of the circuit, that would be us (Schneider Electric), and it isn't I.S. rated.

I'll pass this on to my boss and let him make the decision.


Thanks for all of your help!

John

 

[KentAT]

I am also wondering if the meter is installed in an area classified as a hazardous location.

"Recommending" I.S. wiring is not the same as "requiring" it. If the meter requires I.S. wiring methods, I would expect to see an installation drawing from the mfg that shows their approved wiring method.

What kind of meter is it?

 

[Cmdr_Suds]

To make the installation intrinsically safe, all you would need is an IS barrier or relay module located outside of the hazardous area. Without a hazardous area defined, your just guessing.