Dwyer P72 - Manual (Page 4)

64.7 x 1.00 x 530
114.7 x 1.378 x 560
Qa = 1.00 x = 0.522
5.879
Sv
Mfh = Qm
EXAMPLE: If using a standard meter scale for SCFM Dry Air @ 100 psig, 70°F on
argon (SP. GR. = 1.378) at 50 psig, 100°F., what would the conversion factor be?
Thus, actual flow of argon would be observed scale reading times 0.522.
STEAM
Series P72 flowmeters may be used for vapors such as steam. The conversion
factor may be determined with the following formula:
Where:
Mfh = Actual flow, lbs/hr.
Qm = Meter scale reading, standard.
(SCFM Dry Air @ 100 psig, 70°F.)
Sv = Specific volume of media (from steam tables).
EXAMPLE: When using a standard Series P72 gas meter scaled for SCFM Dry Air
@ 100 psig, 70°F, what is the conversion factor for lbs/hr. steam at 50 psig, 300°F?
Thus, actual flow of steam in lbs/hr. would be the observed scale reading times
2.267.
CORRECTING READINGS FOR NEW GAS CONDITIONS
Qg = Qs
Where:
Qg = SCFM, corrected to new conditions.
Qs = SCFM read on meter scale.
Pg =
Operating pressure, psia (psig + 14.7).
Ps = 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 .
Pg x Ts x ps)
Ps x Tg x pg)
5.879
6.727
Mfh = 1 x
VISCOSITY CONSIDERATIONS:
Each Series P72 liquid flowmeter has a so-called “Viscosity Immunity Ceiling”
(V.I.C.). Usually, if the viscosity of the metered liquid is less than the V.I.C. of the
meter, the accuracy will not be influenced by changes in viscosity. When greater
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.
AVERAGE V.I.C., CENTISTROKES, FOR STANDARD
SERIES P72 FLOWMETERS
100% GPM,
SIZE 6
0.54 - 0.80
1.20 - 2.60
3.80 -7.00
10.0 - 23.0 CTS
3
7
15
25
100% GPM,
1-1/2˝ SIZE
11.0 - 15.0
21.0 - 35.0
50.0
70.0 - 120 CTS
50
100
250
500
MAINTENANCE:
Occasional cleaning of the sight tube and internal sensing elements to assure float
visibility and continued accuracy is the only maintenance necessary for Series P72
Flowmeters. Frequency will depend on the application — in most cases, an annual
cleaning is adequate. It is not necessary to remove the Series P72 Flowmeters
from the pipeline for cleaning or replacing parts. The body remains plumbed into
the pipe, allowing easy service and even installation of different sensing elements
to accommodate new flow rates or fluids.
Upon final installation of the Series P72 Flowmeters, no routine maintenance is
required. A periodic check of the system calibration is recommended. Please follow
the instructions in the manual under “Inspection and Cleaning.” The Series P72
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 contact
customer service to receive a return goods authorization number before shipping.
DISASSEMBLY
BE SURE PRESSURE IS FULLY VENTED AND FLUIDS COMPLETELY
DRAINED BEFORE DISASSEMBLING THE FLOWMETER. WEAR SAFETY
GLASSES AND PROTECTIVE CLOTHING IF THERE IS ANY CHANCE OF
EXPOSURE TO HAZARDOUS CHEMICALS.
The sight tubes of all standard Series P72 Flowmeters may be removed by,
depending on model type: (a) removing the cotter pins and pulling the lock rings
out horizontally; (b) removing the bolts from the body/sight tube flange; or (c)
removing the internal snap ring with retaining ring pliers. Using hands only, pull the
sight tube straight up out of the body with a slight twisting motion, lifting it clear of
the body and snorkel or guide rod. Remove the float assembly by lifting it up and
away from the snorkel/guide rod. The core tube assembly may then be lifted out —
if stuck, CAREFULLY pry up at the top of the slot with a brass rod, taking care not
to damage the body or core tube.
INSPECTION & CLEANING
Inspect parts for nicks, scratches, chips, wear, and contaminant build-up. The
edges of the core tube slot, ID of the core tube, and OD of the piston (largest
section at the float assembly bottom) are precision machined. Damage to these
areas can destroy the meter's accuracy. Also inspect the O-ring, the bottom section
of the sight tube, and the inside of the upper body section. Damage to these areas
may result in leaking. Clean, rinse, and dry all parts carefully, including the O-ring,
preferably with a mild detergent and water and a soft cloth or soft tube brush. If
solvents are used, make sure they are compatible with all meter parts (plastic sight
tubes may be attacked by chemical vapors or solvents —consult the factory).
DO NOT SCRAPE OR USE ABRASIVE MATERIALS FOR CLEANING.
NOTICE
WARNING
F-P72:TEMPLATE 8/19/10 12:11 PM Page 4