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Thanks JL. There's an existing 4-20 XP transmitter and we are looking to loop it to a controller. I too expected that some 1/4 DIN units would be rated Div 2, just haven't been able to find one yet.

Hi folks, I haven't had any luck finding a free-standing PID tmperature controller (actuates a modulating cooling water flow valve) that can be located in a hazardous location. The operators will want to adjust the setpoint at will, and the non-XP control room is some distance away. Quite...

Looking for a lab-scale version of a high shear in-line disperser or mixer, flowrate less than 1 gpm. Most models are much bigger than this. Anyone have any suggestions? TIA

Have you checked out any of the books by Trevor Kletz ("What Went Wrong?", "Still Going Wrong", "Intrinsic Safety in Plant Design"). They are full of case histories over the last 20 years or so, not always fully documented, but the references may help.

It all sounds rather high tech to me...does this need to be an on-line measurement? If so density (the curves for glycol vs temperature are well known) via coriolis flowmeter, or refractive index should work well. Off-line, the same measurements can be made at insignificant cost.

Right, anhydrous HCl is not corrosive to stainless steel. It's water that makes it corrosive. Even superalloys like Monel (used for HCl pressure regulators) can be corroded if moisture is present.

For measurement in gas phase or in solution, there are a number of on-line analytical systems such as React-IR by Mettler-Toledo, or ATR-UV-Vis on-line spectroscopy etc. which can measure concetration of reactants, products, byproducts, etc continuously in real time. They use a diamond-tipped...

Yes I certainly would be curious to know if this is batch or continuous myself. Coming from the fine chemical arena, I automatically assumed he was talking about a batch reactor with a volume say, 50L, which is typical for a batch yield of 1 kg of a solid product such as a crystalline...

A few other manufacturers of oil circulating heaters (TCU's actually): HEAT, Inc., Budzar, Mokon. All reliable and helpful vendors. You might just have a conversation with a couple of them.

Again thanks for your input everyone. It seems I was somewhat ill-informed. Because of other salt complexes in this mixture, it actually contains less than 1% free ammonia in solution. And the history of pressure building up in storage totes was another miscommunication. There has never been a...

Wow! You folks are great. 0.08"H2O certainly is low. That's about as accurate a number as I need at this point. I thank you all. And thanks for the links and references.

Thanks for the references. Apparently, my pressure drop must be pretty small, since the Moody calculator says my friction factor is out of range. Do you think the ASHRAE or SMACNA literature (where can I find it?) has a simple chart I can get a ballpark number from?

Anyone have a good source to estimate pressure drop of air (atmospheric pressure) flowing through pipes (3" to 6" diam). My flowrates are only about 10-15 SCFM. TIA

Thanks for those references. Apparently this material simply off-gases and builds up head space pressure, which now I realize is unrelated to the vapor pressure numbers. We were hoping to use a poly tank, but that looks unlikely. Thanks for your input, folks.

I should add that although the tank will be vented to the atmosphere, we need to keep the ammonia vapors contained as much as possible for odor control and to prevent the pH and chemical composition from changing.

Thanks TD2K So you are saying that the 4psia does not mean 4psig...ok, I'll have to think about that. But the folks in the plant tell me that their 300-gal totes build up a good 5psi on hot days. The conservations vents periodically pop-off to let out ammonia vapors. No 5000 gal polyethylene...

I'm spec'ing out a 5000-gal storage tank for a solution that is essentially 9wt% aqueous ammonia. Perry's says that for 9.5% NH3 on a hot day (at 90F) total vapor pressure can reach almost 4psia. Sizing the conservation vent is not a problem, I'll go with Groth or Protectoseal, but my plans...

Thanks for all of your advice, folks, and for the warning to pay attention to non-standard operations. Yes, that was the type of Crispin valve our supplier recommended, but I think one of the Protectoseal or Groth models will do better, or even the free vent idea. However, I will check with the...

Great references! Thanks. raingal79: It's probably not worth doing the calculations. Just recongnize that the pressure rise can be hundreds or thousands of psig if a dead-ended liquid-filled line heats up. Use pressure relief. The expansion coefficient is handy to estimate the relieving flow...

Hi, we're desigining a 5000 gal SS atmospheric storage tank for non-flammable liquid. Well be filling it at about 100 gpm and draining it at about 30 gpm. I simply need a breather vent to let the air out when filling, and let the air in when draining (its a little smelly so we'll be venting it...