|
APPLICATIONS: The Hersey Model MFMII
® was designed for use as a combined
fire and domestic service meter where one
water line serves both fire and domestic,
or process needs. Also as a master meter
for an entire water system; for water system
zones; automatic sprinkler systems and fire
services; for domestic or process water
systems where low pressure loss and dependable
accuracy over a very wide flow range are
essential. Hersey MFM II Water Meters will
measure accurately at full pipe capacity,
and have the highest flow capability available.
CONSTRUCTION: Hersey MFM II Water
Meters consist of a mainline meter to measure
high flow rates, a bypass meter to measure
the lower flow rates, and a weight and lever
valve (mainline valve) to automatically
control the point at which the larger mainline
meter registers. The valve is self-aligning
and self-adjusting. The bypass includes
a resilient seated isolation valve, a swing
check valve, and depending upon the bypass
meter, either a Hersey MCT II ™ Compound
Meter, Hersey Model MVR ™ Meter or
Hersey Horizon ™ Meter. The mainline
meter maincase is cast iron with epoxy coating
inside and out.
The MFMII is designed with an unobstructed
full flow that eliminates the need for an
external strainer. An internal strainer
protects each measuring element.
REGISTERS: Separate mainline and
bypass registers are provided. Permanently
sealed registers use proven magnetic drive
design and the exclusive Hersey triple seal
to provide clarity and error free meter
reading. Internal gears in all assemblies
are self-lubricating, molded plastic for
long life and minimum friction. The standard
registers include a straight reading, odometer-
type, totalization display, a 360 degree
test circle with center sweep hand, and
a low flow indicator. The Calibrator Gear
Train permits accuracy calibration on MFMII
mainlines and MCTII bypasses. For accuracy
calibration on MVR and Horizon bypasses,
consult the appropriate meter sections.
All Hersey models are available with electronic
meter reading systems for increased meter
reading efficiency. (See
Automatic Meter Reading Equipment)
OPERATION: In normal operation,
during low flow rates all water flows through
the bypass section and is registered by
a sensitive model MCT II compound, model
MVR vertical turbine meter or a Hersey Horizon
Meter (see separate data pages for description
of these meters). When pressure loss through
the bypass section approaches 4 psi, the
mainline lever valve automatically opens
permitting the torrent proportional mainline
meter to measure flow. When flow rate decreases
sufficiently, the mainline lever valve closes,
and all lower flows are again measured by
the bypass meter.
The exclusive automatic lever valve is
controlled by a specially designed weight
which locks the valve in the closed position
until a predetermined pressure loss overcomes
the weight and opens the valve. A venturi
effect causes a precise portion of the total
volume to pass through the torrent proportional
mainline meter. The self-aligning rubber-faced
valve clapper assures a positive seal for
accurate bypass meter registration.
MAINTENANCE: The Hersey MFM II
and bypass meters are designed and manufactured
to provide long service life with low maintenance.
All parts are accessible for in-line service
if needed.
CONNECTIONS: ANSI class 125 flanges
standard.
 |
Model Designation
|
MFM II |
 |
|
Sizes |
3"*,
4", 6", 8", 10",
12" |
|
|
Standards |
Manufactured
and tested to meet or exceed all applicable
parts of AWWA C703, FM approved mainline;
UL listed, ULC classified. |
|
|
Installation |
Horizontal
only with 8x pipe diameter of straight
pipe (same size as meter) on inlet side
of meter. |
|
|
Operating
Flow Range |
See Catalog
PDF below |
|
|
Accuracy |
See Catalog
PDF below |
|
|
Maximum Working
Pressure |
175 PSI |
|
|
Temperature
Range |
33F to 100F |
|
|
Measuring
Elements |
Mainline
= Torrent wheel. Bypass: MCT II = Torrent
Wheel and Nutating Disc. MVR = Rotor.
Horizon = Rotor |
|
|
|
Register
Type |
Permanently
sealed, straight reading, magnetic drive
with low flow indicator. Remote reading
units optional. |
|
|
Meter Connections |
ANSI class 125 standard end flanges.
|
|
|
Materials |
Maincase
- epoxy-coated cast iron; Bypass meter
case - bronze UNSC84400; valve weight,
swing arm and seats - bronze UNSC84400;
Valve discs - elastomer; Casing bolts
- steel
|
|
|
Options |
AMR Reading Systems.
|
| |
* 3"
size is MFM design, not MFM II. |
|
