Recent content by JimD1

A question came up at work, when changing incandescent, fluorescent and HID lamps, does NFPA-70E apply? Is it energized work? Yes, there would be a shock hazard but not a blast hazard. What PPE would you wear? The voltage at the bulb socket for incandescent would be 120 VAC. for the others it...

What are the requirement for PPE / NFPA-70E when replaming 4' fixtures in an office enviroment, HID's, etc? Thanks, Jim

Does anyone know if Rhode Island requires any type of licensed operators for a cogen plant. 400 psi steam, 100k/#/hr boiler, two 4.0 mw gas turbines? Thanks, Jim

OK, I just came out of a meeting. They want to drop the site operating pressure rom 125 psi to 90 psi steam. We are leaving the existing three relief valves set in the neighborhood of 160 psi each offset by 3 psi, we are going to operate at a new lower calculated max firing rate. The boiler...

Puigi, Thanks. There was an engineering decision made to lower the site operating pressure from 125 to 90 since most of the buildings operate with reducing valves and the highest building operating pressure is 60psi. I was concerned that if we had a boiler 'event' that the relief valves may...

Thank you for your reply. We have 3 relief valves, services and calibrated annually offset by 3 psi each set below the max operating pressure of the boiler. I was told that if we drop the normal operating pressure there would be more water in the boiler to flash into steam if there was event...

I have two 70-klb/hr boilers running at 125 psi. The management team wants drop the site operating pressure down to 90 psi. I was informed that I need to add relief valves to the boilers due to the decreased operating pressure in the case of an 'event'. This doesn't make sense. Can someone...

Thank you, are IEEE's the same as NFPA's?

The NFPA -70E has 6 classes for arc flash, class 0 class 1 - 4 cal/cm2, class 2 - 8 cal/cm2, class 2* - 8 cal/cm2 class 3 - 25 cal/cm2, class 4 - 40 cal/cm2 How does this compare with the NESC? Thanks, Jim

Thank you both for your answers. I'll have to research what's on the walls. Jim

If you have an explosion proof receptacle, is it also waterproof. I have a production facility where they are washing the walls with a high pressure nozzle. The walls have explosion proof receptacles on it, I assume that they would also be water tight? Jim

If I don't have the mfg's data, but I do have flow velocities, pressure drops and temp differenced, is there a way I can determine flow in GPM? Jim

What is the formula to calculate a chiller bundle flow in GPM if the only info you have is the delta T in Fahrenheit and the pressure drop across the bundle in ft/min? Jim

Yes, overcharging will increase the pressure and temperature to a point, but as you continue to overcharge the pressure will level off and the temperature on the liquidline will decrease and the superheat on your suction line will decrease until you flood back. An overcharge will not...

A few of my co-workers are in a discussion about causes for a high liquid line temperatute og an A/C and or refrigeration system. A few of the causes that they list that I don't argee with are : 1. Over charge 2. Bad Valves 3. Partially clogged cap tube or defective TXV As for over charge, I...