Making a large battery

[KeepItSimpleStupid]

Dr. P.

The last one I installed used one of these for air velocity measurements: https://www.dwyer-inst.com/Product/AirQuality/AirVelocityTransmitter/Series641#specs the shutdown was part of a PLC based system, The deal is, you have to be able to see the display when cleaning/commissioning/installing, so the local readout makes a LOT of sense. The model this one replaced was much larger and didn't average. These are pretty nice.

They also had a DIN readout/power supply/alarm unit. As I said, you have to pull out, clean the dust and re-install/reposition. Our frequency was like every 4-6 months.
Fire alarm testing generally caused the cleaning to occur. these systems used Hydride gases like Silane, Diborane, Arsine, phosphine etc. Definitely, not good stuff. the stupid one was for a Hydrogen Selenide reactor. If everything worked, the effluent should have been scrubbed. Those labs had 100% make-up air.

The other ones used were a Dwyer Magneheilic differential pressure gauge (inches of water) with a pointer. I'm not sure exactly how it was plumbed. e.g. https://www.dwyer-inst.com/Product/Pressure/DifferentialPressure/Gages/Series2000-SP There's a whole bunch of other choices: https://www.dwyer-inst.com/Products/CatalogSearch.cfm the most nasty stuff was Bromine Methanol and some cyanide compounds. Most hoods were equipped with an acid neutralizer and the nasty-est was concentrated Hydrofluoric Acid. Only one hood was designated for use with HF and it wasn't a daily thing. When I was working with HF, safety was a bit more lax and I may have used the stuff once every two weeks or so. That's a training video you really need to see. Very nasty stuff. I have some stuff at home that contains about 1% HF and 1% Hydrochloric.

In some cases, you may need to use a room differential pressure sensor.

FWIW: Dwyer also makes some differential pressure switches that seem to be pretty reliable. One was used in a 1000 W tube RF transmitter. Replaced it once in maybe 30+ years.

Never sent any of Dwyer's stuff back for repair except the 30 YO broken sensor.

FWIW: These **broken link removed** are very nice flow switches. We only used it on a Scanning Electron Microscope. the cost is pretty high. GemsSensors makes some inexpensive water flow switches. In one case, we just used a visual rotary water flow sensor. Our water had a lot of iron in it. The lab should have had a central chiller for 50 deg F water. One was actually engineered and shown to have a decent payback, but not directly. We had no incentive to reduce our water use and it was a lot just for cooling,

 

[dr pepper]

Thanks kiss.
Yes actually now you mention it I have come across magnahelic before, on powder coating plant, I think it was part of the extract system, and here there is some photohelic guages on some plasma generating plant, but I have not seen dwyer fume cabinet monitors I didnt know they did that kind of stuff, I'll look into that.
I'd rather not go to the extent of a plc on this cabinet, at the moment it just has a motor starter, a system that opens the coil circuit is fine, unless these days your sposed to fit a safety relay, that can be arranged if I have to, if there were multiple blowers oan or multiple hoods yes I'd use a step7 or a logo or something.

 

[KeepItSimpleStupid]

So, the velocity xmitter requires some sort of alarm module. The display I used also had an aux power output, so something like this https://www.redlion.net/product/iams-dual-setpoint, if you don;t want to see it. There has to be any number of solutions. So, the original sensor had a DIN (82mm x 82mm or so) panel mounted display/aux PS/alarm module that required 120 VAC in. I think what I did was, I left the display as a % of some full scale number. e.g 33.3% would be displayed and a label affixed that said: 1000 ft/min FS (Alarm at 22%),

My boss was like people like numbers between 0 and 10. He'd stretch that to 0-100. If the number was supposed to be negative, the - sign was always dropped in conversation.So, KilloPascals is nuts in my opinion, A 19" rack panel makes more sense than a xxxx mm rack panel. Just like 1RU, 2RU makes even more sense. Then there is DIN, 1/2 DIN, 1/4 DIN and the cutout sizes are different with and without sleaves. Besides that, I like to be able to estimate lengths using body parts.

 

[dr pepper]

Yep that looks about right, not too bothered about a display, the people using the hood are no scientists, some are more akin to monkeys, so not having a guage is less to moan about or make excuses, I was thinking a red/green light.
I'll have a look at those, might get a rep in to talk it over.

We humans have only been using units of measurement of any kind for a fraction of the time we've been on the planet, so its easier to imagine 10 hands, or 3 feet than a mile or 10 miles.

 

[KeepItSimpleStupid]

They had a Magnehelic with a LED. I think you have to supply DC power. The gauge had the movable pointer option. You could probably order both options.

The expensive one, the one with the thermal conductivity probe absolutely needs a display that you can SEE from where the sensor is positioned.

The deal is:
1) A section with laminar flow. I think it's 5 diameters away from a bend.
2) Locate in the center of the duct (hence different lengths)
3) Rotate and insert until the measured flow is at max

You need to do thus at install and every cleaning.