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- Users: twainagain
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Explosion Proof HVAC
Isn't there some way to remote-drive the equipment so that the motors and controls are not in a C1/D2 zone? Is there some sort of belt-drive and air-control logic that could work? Not my area, but such approaches might qualify as intrinsically safe. Don- twainagain
- Post #3
- Forum: HVAC/R engineering
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HEPA filters & safe change boxes
Don't forget dust fire protection. If the filter's dust is conductive or combustible, the filter change area might need to be upgraded electrically (see NFPA for regulatory capture criteria). Don- twainagain
- Post #9
- Forum: HVAC/R engineering
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Blower/Fan Performance
I'm not an expert, but, after a few minutes with the equations of state, I recall that we find work produced by a fan or a pump is change in head (corresponds to your change in "static pressure?") times mass flow rate... in other words, for fans, it's the product of cfm and delta p...- twainagain
- Post #10
- Forum: HVAC/R engineering
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Blower/Fan Performance
I'm not an expert, but, after a few minutes with the equations of state, I recall that we find work produced by a fan or a pump is change in head (corresponds to your change in "static pressure?") times mass flow rate... in other words, for fans, it's the product of cfm and delta p...- twainagain
- Post #9
- Forum: HVAC/R engineering
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HVAC and The Slide Rule..!!
The issue is competence and capacity. I'm happy to have a slip-sticker on staff any day. That said, I hope everyone isn't surprised that there are tons of us "suits" who rebuilt engines as childhood projects, who were mechanical fitters in college, who knocked out our engineering...- twainagain
- Post #4
- Forum: HVAC/R engineering
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Control System Design Philosophy
One cost to be figured is that of special service calls and trips where the user is needlessly baffled by the PLC. I love the little Omrons myself, but the $100 savings won't buy much of my time. Also, when the PLC fails, they're starting over, especially if the manufacturer has gone belly...- twainagain
- Post #6
- Forum: HVAC/R engineering
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Shooting range ventillation
I can't help you with the lead treatment, but I have some unsolicited, out-of-scope, hot policy opinions (HPO) about shooting practice. Consider requiring jacketed bullets; my guess is that copper dust is safer (and prettier) than lead dust. They're less accurate, but not in a left versus...- twainagain
- Post #2
- Forum: HVAC/R engineering
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Looking for good mechanical eng. handbook
Do your engineering student friends a favor and buy them a Marks for their freshman year. They should take it everywhere, compare sample solutions to their course texts, and tab out everything as they go. Then, come EIT time, they have the perfect, single resource. When they start that first...- twainagain
- Post #4
- Forum: HVAC/R engineering
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Position of the evaporator Vs performance
Is this a TXV system? Some TXV are finicky about orientation.- twainagain
- Post #2
- Forum: HVAC/R engineering
