Dwyer TVF - Manual (Page 4)

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 0.622.
STEAM
Series TVF 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 TVF 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.
VISCOSITY CONSIDERATIONS:
Each Series TVF 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.
CAUTION: 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!!!
DISASSEMBLY
The sight tubes of all standard Series TVF 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. On Series TVF
models, the spider ring, O-ring, will come out with the core tube.
If the core tube is stuck, try removing the metal spider ring first.
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).
CAUTION: DO NOT SCRAPE OR USE ABRASIVE
MATERIALS FOR CLEANING!!!
AVERAGE V.I.C., CENTISTROKES, FOR STANDARD
SERIES TVF FLOWMETERS
100% GPM,
3/4˝ SIZE
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
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
5.879
6.727
Mfh = 1 x