Dwyer HFPS - Manual (Page 2)

INSTALLATION DOS AND DON'TS
To obtain satisfactory operation from a HFPC & HFPS meters, the following
points should be considered:
DO:
•
install a pressure gauge near the inlet of the meter
• place throttling valves at the outlet of the meter
• use pipe sealer on the connections
• install solenoid valves at meter outlet (as far downstream as possible)
• mount in any orientation: vertical, horizontal or upside down
DO NOT:
•
place restrictions between the meter’s pressure gauge meter inlet
• use in systems where reverse flow is possible
• place meter in non-aligned piping
• over-flow the meter by more than 150% of maximum reading
• operate at pressures and temperatures greater than specified
• be mounted near hot pipes or equipment which can cause damage to
the pressure vessel
• use in systems where the assembled piping is not supported.
Externally applied piping forces may cause the meter to rupture or
malfunction.
OPERATION
The meters are tubular, with all internal wetted parts sealed within the body
casing (5). Running through the center of the body casing is a tapered
center shaft which is centered in the bore. Encircling the shaft is a sharp-
edged, floating metering poppet (6). The metering poppet is held in the “no
flow” position by the biased return spring (4). As the flow moves through
the meter it creates a pressure differential across the floating orifice disk,
forcing the disk and transfer magnet against the return spring. As flow
increases, the pressure differential across the metering poppet increases,
forcing poppet to move along the tapered center shaft. As flow decreases,
the biased return spring forces the poppet down the tapered center shaft,
returning to the “no flow” position.
Reading the Meter
Notice the black reference line which runs 360° around the metering
poppet. This reference line moves under the scale in direct relation to the
movement of the poppet. When fluid is flowing, the flow rate through the
meter is read by lining up the black reference line with the closest rate line
on the flow scale.
Specific Gravity or Density Effect
Standard meters are calibrated for WATER with a specific gravity of 1.0.
The floating disk meter is affected by fluid density as are most other similar
type meters. HFPC & HFPS meters have less of this effect because of the
sharpness of the floating orifice disks being used. The indicated flow
reading will read high for heavier fluids and low for lighter fluids. A corrective
factor can be applied to the standard scale or a special scale can be
added at additional costs. When measuring fluids with other specific
gravities, the basic equation below can be used to develop corrected
readings.
CONTAMINATION AND FILTRATION
Recommended Filtration
System filtration of at least a 74 micron filter or a 200 mesh screen is
recommended. It has been found that if inadequate filtration has caused
meter failure, it will normally fail in the open position. Some systems may
require a magnetic filter. IMPORTANT: Meter damage caused by excessive
contamination is not covered under warranty.
Stabilized Contamination
The goal of filtration is to create effective protection from system
contamination. Proper filtration stabilizes contamination to allow fluid
components to function properly. A fluid system is considered stabilized
when, “contamination in” equals “contamination out”. Proper filtration must
reduce initial contamination to a stabilized level within an acceptable time
period. The system should be stabilized in time to prevent premature wear
or damage to meter components.
MAINTENANCE
Upon final installation of the Series HFPC and HFPS Plastic Flow Meters,
no routine maintenance is required. A periodic check of the system
calibration is recommended. The Series HFPC and HFPS is 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.
DWYER INSTRUMENTS, INC.
Phone: 219/879-8000 www.dwyer-inst.com
P.O. BOX 373 • MICHIGAN CITY, INDIANA 46361, U.S.A. Fax: 219/872-9057 e-mail: [email protected]
Figure 1 (Flow Meter Cross Section)
©Copyright 2007 Dwyer Instruments, Inc. Printed in U.S.A. 5/07 FR# R1-443560-00
F-71 5/10/07 3:59 PM Page 2