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Vinegar manufacturer questions on NGS safety


Acetofactor

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Hi, I'm a small vinegar manufacturer recently tasked with making a white distilled vinegar-like product that uses diluted NGS (95% ethanol) to make the vinegar. Most other vinegars I have made in the past were from wine or fermented ale/fruit wine so all the safety implications of this are new to me. Any help is appreciated.

To start, I followed the fire marshall's request and had an engineering report done to confirm 1 hour ratings on my fire walls in my unit. I am approved for up to 120 gallons on-site since I don't have sprinklers but I only keep 55 to be safe. I set up an area away from electrical and flammables where I have the drum (NGS comes in 55 gallon steel drums) on a steel pallet grounded to a grounding rod my plumber installed. I use a stainless steel hand operated pump that is bonded with the drum and grounding rod to pump the ethanol.

Now, I have traditionally used HDPE plastic drums and given the dilute and corrosive nature of my product, regular steel drums, even lined ones, won't work since they will corrode in like a day. Right now I am filling the HDPE drums with water about 80% full then pump in the ethanol. I have a stainless steel ladle that is bonded to the pump in the water in the drum since I can't ground a plastic drum. Outside of the NGS drum, I store ethanol at 15% ABV. I have a few other questions though.

1. Do I have to wear static resistant clothing when using ethanol? I only have cotton work shirts and threw away the polyester ones to make sure there wasn't an issue but if I need to buy hard core anti-ESD gear, let me know. Same with footwear?

2. Do I need a flame arrester in my pump? I can't tell if flashbacks are a big thing with ethanol or not.

3. Should I dilute all the NGS immediately or is it ok to store residual in the drum as long as it is closed tight and grounded?

4. Do I really need a flammable liquid cabinet? It wasn't brought up by the fire marshall and I just passed my latest inspection. My neighbors in my industrial building have used industrial oil in drums on metal pallets (grounded and bonded) and don't have cabinets either.

5. NFPA says you can pump up to 5 gallons of class IB or IC into HDPE containers (UN1H1) I did this once (not correctly) making 50% ABV in a plastic bucket though it made me real uneasy in retrospect since plastic can't be grounded, even with the closed UN1H1 containers. Would a bonded stainless steel funnel make this ok?

P.S. I have a large CO2 extinguisher on standby at all times. Knock on wood I haven't had issues yet.

Just to note,  I will be taking the Dalkita static class this week.

 

Thanks for any help.

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The LyondellBasell company used to put out a very comprehensive guide to using and storing alcohol but I don't see it on their web page anymore.  Copies of useful documents like this do float around the web and if you search for "Equistar Ethyl Alcohol Handbook" you will probably find a copy somewhere.

A long time ago when I worked for an NGS supplier we delivered to many backyard vinegar manufacturers with essentially no safety measures in place.  Dealing with NGS is not like working with dynamite, but you do need to be careful. Eventually the regulations were changed here and suppliers became responsible to ensure that they did not deliver to unsafe premises and then we would send out technical people to advise the customers.  Your supplier may be able to do the same for you.

Regarding your specific questions

1. Our staff wore standard overalls and safety shoes. Of course there must be no smoking and no matches or unprotected electrical gear or phones allowed.

2. I have never seen a flame arrester on a pump.  The pump discharge should be below the liquid surface in the receiving tank to prevent alcohol from falling through air as this can generate static charges. The vents to atmosphere mostly had flame arresters as far as I remember.

3. Even if you do dilute the NGS the vapors above the liquid can be flammable. I once saw a wine tank explode when the lid was welded while there was wine in the bottom of the tank.

4. I guess flammable liquid cabinets are a good idea in a laboratory, but I have seen plenty of NGS samples standing around on lab benches.

It seems to me that you are tackling this matter thoroughly and if you follow the fire marshall's instructions you won't go far wrong.

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We always used steel or stainless piping for the dip pipes so I don't know about plastic tubing.  The aim was to prevent the alcohol from falling through the air so I would imagine that plastic would be fine if the rest of the piping is plastic.  It's a long time ago but I seem to recall there being a limit on the flow velocity to avoid static build up.  From what I remember the velocity limits were rather high (> 4 m/s ??) and we never approached them in normal operation.  Your fire marshall may be able to advise on this as gasoline would have similar restrictions.  This must be a common occurrence in distilleries and hopefully one of the other members can give you current advice for your area.

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24 minutes ago, meerkat said:

We always used steel or stainless piping for the dip pipes so I don't know about plastic tubing.  The aim was to prevent the alcohol from falling through the air so I would imagine that plastic would be fine if the rest of the piping is plastic.  It's a long time ago but I seem to recall there being a limit on the flow velocity to avoid static build up.  From what I remember the velocity limits were rather high (> 4 m/s ??) and we never approached them in normal operation.  Your fire marshall may be able to advise on this as gasoline would have similar restrictions.  This must be a common occurrence in distilleries and hopefully one of the other members can give you current advice for your area.

Yeah, I talked to my pump manufacturer and I think around 9 gpm / 34 lpm was the limit on flow velocity but don't quote me.

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