Dwyer SSM - Manual (Page 3)

CORRECTING READINGS FOR NEW GAS CONDITIONS
Where:
Qg=SCFM, corrected to new conditions
Qs=SCFM read on meter scale
Pg=Operating pressure, psia (psig + 14.7)
Qs=Pressure stated on scale, psia (psig + 14.7)
Tg=Operating temperature, absolute (˚F +460)
Ts=Temperature stated on scale, absolute (˚F + 460)
Pg=Specific gravity of metered gas
Ps=Specific gravity stated on scale
Qg = Qs
√
Pg x Ts x Ps
Ps x Tg x Pg
EXAMPLE: If using a standard meter scaled for SCFM Dry Air @ 100
psig, 70˚F on argon (SP. GR.=1.378) at 50 psig, 100˚., what would the
conversion factor be?
Thus, actual flow of the argon would be the observed scale reading
times 0.622.
STEAM
Series SSM gas flowmeters may be used for vapors such as steam. The
conversion factor may be determined with the following formula:
Mfh = Qm _______
Where:
Mfh=Actual flow, lbs/hr.
Qm=Meter scale reading, Std. (SCFM Dry Air @ 100 psig, 70˚F)
Sv=Specific volume of media (from steam table)
EXAMPLE: When using a standard gas meter scaled from SCFM Dry Air
@ 100 psig, 70˚F, what is the conversion factor for lbs/hr. steam at 50
psig, 300˚F?
Mfh =
Thus, actual flow of steam in lbs/hr. would be the observed scale reading
times 2.267.
ViScoSitY conSiDeRationS
Each liquid flowmeter has so-called “Viscosity Immunity Ceiling” (V.I.C.).
Usually, if the viscosity of the metered liquid is less than the V.I.C., the
meter will be influenced significantly, and must be calibrated for that
viscosity. Effects of viscosity on a given flowmeter are not always
predictable. Two apparently similar liquids with comparable densities
and viscosities may impact meter calibrations quite differently. The table
below provides general guidelines for the typical maximum viscosity for
meter models without affecting accuracy.
Qa = 1.00
√
64.7 x1.00 x530
114.7 x1.378 x560
= 0.622
5.879
√Sv
5.879
√6.727
aVeRaGe V.i.c., centiStoKeS, foR StanDaRD
“tHRU VieW” fLoWMeteRS
100% GpM,
3/4˝ MeteRS
0.54-0.80
1.20-2.60
3.80-7.00
10.0-23.0 100% GpM,
1-1/2˝ MeteRS
0.54-0.80
1.20-2.60
3.80-7.00
10.0-23.0
ctS
0.54-0.80
1.20-2.60
3.80-7.00
10.0-23.0 ctS
0.54-0.80
1.20-2.60
3.80-7.00
10.0-23.0
Maintenance
Upon final installation of the Series SSM All Metal Flowmeters, no
routine maintenance is required. A periodic check of the system
calibration is recommended. The Series SSM All Metal Flowmeters are
not field serviceable and should be returned if repair is needed (field
repair should not be attempted and may void warranty). Be sure to
include a brief description of the problem plus any relevant application
notes. Contact customer service to receive a return goods authorization
number before shipping.