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I have a 50,000 lb/hr high pressure boiler. In setting up the controls I have a dilemma. NFPA 85 calls for - 8 air changes, with the air dampers driven to their full open position- in one area, but in another section calls for only a- 15 seccond purge at prior setting air flows-with a boiler...

In ASCE 7-10, under wind loading Table27.4-5 shows Cn factors for Pitched Free Roofs, Open Buildings. There is a column listing values for Case A and Case B. Can someone tell me what Case A and Case B refer to?

I need a shell and tube heat exchanger to heat a liquid from 170 F to 200 F. I have steam at 120 psig available on the shell side. What do I use as my Delta T? Assuming 5% moisture, I am down to about 30 psig steam equilibrium. That gives me a LMTD of about 30 F. Am I on the right track, or...

I am modeling a tank with RISA. I am using the special shapes assist. I need to modify my input on the hydrostatic tank loading. Is there any way to do that other than to create a new model?

I have a four pass drum dryer that we intend to use to dry agricultural products. No information is available from the original dryer manufacturer as to air pressure drop through the dryer. What would be a typical pressure drop used in this type of application, or how would you typically...

Thanks to everyone for their input. My thought is for a publication like this to put in such a load factor and then not define how they intended it to be interpretted is bizarre. We will use the worst case conditions and muddle on.

I am doing design on an open building with monoslope roof. ASCE 7-05, Figure 6-18A has values for Cnl and Cnw, but it references Load Case A and B. I can find no clarification of what Load Case A and B are in the document. Can anyone help? Thanks

Thanks for the responses. Regarding VPL's comments on the heat exchangers, did they fail because of pressure or vacuum? With liqiod to liquid heat exchangers and limited temperature available, it seems that release of a small amount of liquid would relieve the pressure. Not good, but not a...

I have a shell and tube heat exchanger, designed to handle a glycol solution at 200 Deg. F on the shell side, and water at 190 Deg. F on the tube side. Both flow paths have isolation valves on their inlet and outlet piping, so they could be isolated and thermal expansion of the liquid come into...

Good point, RMW. We were looking at staggered tubes, but may need to consider in line arrangement with soot blowers. Also, what is anyone's experience with Heresite coatings for corrosion protection?

We are heating process water, with glycol/water exit temp of 140 F and gas exit temps of 100 F. Pressure on water side is estimated at 50 psig. Chloride attack should be minimal, but sulfide concentrations and corrosion on the gas side is a major concern.

My concern is not so much with the tubing, as we are circulating a glycol mix at relatively low pressures. The questionable component is the fins with possible corrosion attack. pH of condensate is anticipated to be above 4.0, but will not know for sure until 10% biogas is burned in boiler...

We are considering installing a condensing economizer on a NG fired boiler which will also be fired with 10% biogas. Concern is H2S, with approximately 400 ppm H2S in condensate. Materials proposed are 304 SS tubes and 1100 Al fins. Is this a proper application, or do we need to go to 304 or...

Am trying to get a handle on what I need to worry about on high density dairy ag waste. Typical phosphate limits are 40 ppm before limits come into play for rate of application. State ag dept allowing 200 ppm without imposing restrictions. Am not so concerned about phosphate, as they say it...

Nickelmet, The system I'm working on is for a manufacturing plant with an output of over 100,000 lbs/hr of steam. While piping is part of the problem, a greater concern is material for a large storage tank which will serve as a surge tank for the output from the RO system. Whether special...

We are doing design on installing a Reverse Osmosis system for a boiler make up water system. Preliminary design calls for the RO system to treat the water before it goes to the softner. Limited experience with RO systems in the past have raised concern with corrosion potential in piping. Any...

Dairy CAFOs are having a major problem with odors in area, particularly if they use flush system. Recently worked on aerobic treatment system for dairy waste which seemed to help the odor problem once the bugs got working. After one season they went to direct land application in the summer at...