Plastic Tank in a Classified Area

[RJB32482]

Hello,
We have a silicone storage tank in a Class 1 Div 2 area. Even though silicone is not flammable, there might be a slight concern that flammablew vapors could get into the tank and a spark from transferring silicone could cause an issue. Here goes some other things pertaining to this:

- silicone is a conductive fluid
- silicone transfer rate into the vessel is very low (around 1 ft/sec)
- silicone gets transferred there only once a week
- there is no dip tube in the tank
- tank is atmospheric

From past experience, any thoughts on issues with not having the tank bonded or grounded because its plastic? I don't think so because of the slow transfer rate and conductivity of silicone (even though there is no ground for the charge buildup to go to).

Thanks.

 

[moltenmetal]

Is the piping to/from the tank metallic, or plastic too?

 

[RJB32482]

Piping to and from the tank is 304 stainless steel.

 

[Unotec]

If your electrical equipment meets C1Div2 the tank, itself, should not be an issue. It is the electrical equipment that needs to meet classification.

<<A good friend will bail you out of jail, but a true friend
will be sitting beside you saying ” Damn that was fun!” - Unknown>>

 

[eng3000]

Regarding silicone conductivity, that depends upon exactly which of the very many silicone fluids you're dealing with.

Thermally conductive, yes, but many silicones are not electrically conductive and are in fact used as insulators.

Generation of charge during transfer would depend on a number of factors. If you think you're going to get a charge build up then you need to have some way of dissapating that safely.

If your stainless steel tube is properly bonded then you may only need to consider flow into/through/out of the tank.

 

[JLSeagull]

Chemicals for injection packages are sometimes stored in plastic tanks in hazardous areas even on offshore platforms.

 

[MJCronin]

RJB..

Review NFPA-30....it contains requirements for metallic tanks in both flammable and non-flammable service.

Also compare the cost of the plastic tank versus a production grade thin-walled 304SS tank....probably not much difference.

-MJC

 

[RJB32482]

What you think minimum/max velocities should be (or should I look at the NFPA documents)?