thickness of housekeeping pad
thickness of housekeeping pad
(OP)
How do you determine how thick to make a concrete housekeeping pad, or do you just assume that a 4" or 6" thick pad will be sufficient for most cases?
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thickness of housekeeping pad
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RE: thickness of housekeeping pad
RE: thickness of housekeeping pad
RE: thickness of housekeeping pad
Can anyone give some detail of the trap configuration for blow thru unit?
Thanks in advance for advise.
RE: thickness of housekeeping pad
I don't know where you're located but the securing of plant to a "houskeeping" pad may be subject to seismic requirements also. Particularly with regard to the closeness of the hold-down anchors to the edge of the pad.
Comment re sfxf:
40 inches static! That's a staggering pressure for an air handling unit. Is it an industrial application?
RE: thickness of housekeeping pad
Tell me when your going to turn that air handler on,
we can check with the National Geologic Event Agency
and see if they record any seismic activity on their equipment.
Is that for a wind tunnel ? I hope your ductwork
don't colapse and get sucked into the fan.
Sorry about the jokes, but wow, that's a lot of pressure.
Improper trapping leads to several problems. If the trap outlet is too short
the negative pressure created at system start-up will pull water from the trap into the air handler. The "seal" is destroyed, producing the same effect as an untrapped system. If the trap outlet is too tall
negative pressure will prevent drainage, causing the condensate to back up into the system resulting in property and equipment damage.
RE: thickness of housekeeping pad
The AHU is on during the day and
off at night.
Wilg,
Thank you for the reply. The two fitures
are draw-through AHU. In my application,
it is blow-through. It should be positive
pressure at the outlet of the drainpan.
Do we still need the pad to be 41 inches
high? I don't quite understand why.
Thanks again for help!
RE: thickness of housekeeping pad
Trane has a detail on their website for blow thru coil trapping.
I wouldn't mount it on a 40" high concrete base, i'd look into a structural steel frame.
RE: thickness of housekeeping pad
Minimum condensate drain size:
0-20 tons.... 1"
21-40 tons.... 1-1/4"
41-60 tons.... 1-1/2"
61-100 tons... 2"
101-250 tons... 3"
251 & larger... 4"
AC condensate flow...
Range: 0.02-0.08 GPM/ton
Average: 0.04 GPM/ton
Unitary Packaged AC equipment: 0.006 Gpm/ton
Air Handling Units (100% outside air): 0.100/gpm/1,000 cfm
Air Handling Units (50% outside air): 0.065/gpm/1,000 cfm
Air Handling Units (25% outside air): 0.048/gpm/1,000 cfm
Air Handling Units (15% outside air): 0.041/gpm/1,000 cfm
Pipe size shall not be smaller than drain pan outlet.
Minimum size below grade and below ground floor shall
be 2-1/2". Drain shall have a minimum slope of 1/8"/ft
Verify pipe sizing and discharge requirements with
local authorities and codes.
Depth of trap must exceed by one pipe diameter the
total static pressure of fan.
Try this web site:
http://www.hpac.com/member/archive/pdf/2001/1001/brusha...
Here are some interesting trap details:
You need the 41 inch high trap because you don't want 40 inwg of air pressure to be blowing into your mechanical room.
RE: thickness of housekeeping pad
Theoretically if you have a fan generating 6” of static you need a trap which is 6” deep plus a safety factor to take care of any surges. If it’s a blow-through configuration the interior of the air handler casing will “see” positive static pressure. If it’s a draw-through configuration the pressure will be negative. Either way, I’d contact the manufacturer and get them to calculate exactly what the pressure will be because when the air comes off the fan there’s a velocity component i.e. it’s not all static. Within the casing, the static pressure, at the point where you need to put the drain may only be ¾ of fan static. Your pad doesn’t need to be as high as the water seal is deep. I’ve seen these water seals in the ceiling of the floor below – is that possible? Rather than build a pad over 40” high I’d dig a bloody hole (i.e. form a sump) in the plant room floor if it’s on grade. Just thinking out loud here – what about a steam trap type of device? They’re designed to let liquids pass and close off when the gas tries to pass through.
RE: thickness of housekeeping pad
It is a good idea to use steam trap type of device. THe liquid drain traps by Spirax Sarco will work.
Thank you very much!
Sfxf
RE: thickness of housekeeping pad
Regards,
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