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Nortec "MH"
Humidifier
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The
"MH" is an evaporative high duty humidifier with the lowest
energy cost per 1,000 lbs/hr of any technology. Compliments
Green/LEED designs. Perfect for Data Centers, laboratories,
manufacturing, health care facilities. Easily installed in central
station ahu's or ducts with zero absorption distance. Suitable for
DI/RO softened and potable water applications. Here's the link to
the product data: http://www.humidity.com/data/pdfs/public/09_460_1_MH_Brochure.pdf(1).pdf
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B&G
Triple Duty Valves
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We've
had some recent discussions about pro's and cons of using triple duty
valves (TDV) so thought we'd share the following from the B&G Bulletin
B-821F:
Within
ASHRAE 90.1, Section 9.4.10.3 addresses hydronic system balancing and
states that hydronic system balancing shall be accomplished in such
a manner to first minimize throttling losses. The intent is to
substantially reduce the throttling to minimize the energy loss and to
apply valves that do not increase the overall building energy costs.
"Line
sizing" the valve to match the pump discharge piping is a common
method that engineers have used for selecting the valve size.
Unfortuneately, this method results in oversizing the valve in many cases
and can result in:
- Higher overall operating costs
(higher HP usage)
- Higher "first cost" for
the valve
- The possibility of damage to the
valve seat due to "wire draw".
Proper Triple Duty
Valve sizing should consist of selecting the TDV as a true calibrated multiturn
balance valve (ie..Cv rating), (not like a 1/4 turn
on-off throttle valve).
From
a real project bid recently, plans showed a B&G 1510-4E pump
selected for 500 gpm at 85 ft hd. The pump suction and discharge
lines were shown as 8" . Selecting for 500 gpm TDV's
provided the following options:
- Model 3DS-4S with 2.21 psi
differential (5.1 ft)
- Model 3DS-4B with 6.93 psi
differential (16 ft)
- Model 3DS-5B with 1.96 psi
differential (4.53 ft)
With the pump
selected with a 4" discharge, we would recommend using the 3DS-4S
model. Clearly a 6" or 8" TDV would be oversized and
require substantial throttling to get enough differential pressure to
even read on a meter.
The
TDV includes a non-slam check valve (actually bubble tight shut-off
valve, balance valve, and non slam check valve) in a single valve body
saving first cost and installation cost of installing 3 separate
valves. The TDV also includes brass readout valves for hooking up
to a separate readout meter to obtain differential pressure of the valve
and a calibrated nameplate and adjustment stem. The valve stem provides a
range of 10 to 100% degree of opening of the valve and the stem is a
multi-turn (8-9 turn) valve for fine tuning the adjustment. The
stem can also be backseated to allow re-packing the stem while in
operation under pressure. Valve bodies are provided as standard
with cast iron bodies and brass seats with stainless steel stem and
springs. Standard working pressure is 175 psig with ductile iron
available optionally for up to 300 psig working pressure.
If
your balancing contractor doesn't like you using triple duty valves, the
problem is likely that you're designer is sizing them by line size
instead of by flow rate. B&G offers multiple Cv's for sizes
3" and larger. Selection by flow rate may or may not be the
same as the pipe size, but let's size them correctly and provide the
owner with a valve that has the full functionality needed at the
discharge of the pump, saves first cost and labor cost to install, and
meets the intent of Ashrae 90.1
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