Powers 596 User Manual
Technical Instructions
Description n
Powers Flowrite II Water Mix (MI) Valves combine hot and
cold water proportionally to satisfy the demands of the controlling instrument.
The valve's linear inherent characteristic produces equal
changes in flow per unit of valve stroke regardless of plug
position. The valve is air operated and can be used in a variety of mixing applications.
Specifications n
VALVE
Body Sizes: ................................ 2 1/2" – 6"
Body Material: .......................... Cast Iron
(per ASTM A126-93 Class B)
End Connectors: ....................... 125 # Flanged
(per ASNI B16.1-1993)
Trim: ........................................... Bronze
Packing: ..................................... Spring loaded TFE packing
Seat Leakage: ........................... ANSI Class III; <0.1% leakage
Cv Range: .................................. 74-390
Rangeability: ............................. 100:1
Characteristics: ........................ Linear/Mixing
Maximum Pressure: ................ 200 psi @ Temp. <150°F
Max. Differential Press.: ......... 50 psi
Temperature Range: ................ 40 – 281° F
ACTUATOR
Housing Construction: ............. Die cast aluminum
Diaphragm Construction: ........ Replaceable molded neoprene
Diaphragm Area: ...................... 46 in2, 100 in
Maximum Press. and Temp: .. 35 psi and 200°F
Ambient Shipping Limits: ........ -40 to 220° F
Ambient Operating Limits: ...... -20 to 220° F
Air Connection: ......................... 46 in2 1/4" NPT
100 in2 1/8" FNPT
Position Indication: .................. 1/8" increments
Mounting: .................................. In any upright position with
actuator head above 45° of the
center line of the valve body.
Actuator head may be swiveled
to any convenient position.
Table of Contents n
Description ..................................................... 1
Specifications ................................................ 1
Application Information ............................... 2
Theory of Operation ..................................... 2
Valve Sizing and Selection ...................... 3-4
Close Off Data ................................................ 5
Temperature/Pressure Ratings ................. 5
Dimensional Data ......................................... 6
Installation ...................................................... 7
Maintenance ................................................. 7
Ordering Information .................................... 8
2
IS-P-596MI
Flowrite II
Iron Body Series 596 MI
596 MI with 46 in2 actuator shown
Sizes Actuators Available
2 1/2" 46 in 2 or 100 in 2 Diaphragm
3" 46 in 2 or 100 in 2 Diaphragm
4" 46 in
5" 100 in 2 Diaphragm
6" 100 in 2 Diaphragm
!
WA R N I N G
FAILURE TO COMPLY WITH PROPER INSTALLATION AND
MAINTENANCE INSTRUCTIONS COULD CONTRIBUTE TO
THE VALVE FAILURE.
Watts Hot Water Master Tempering Valves cannot be used
for tempering water temperature at fixtures. Severe bodily
injury (i.e., scalding or chilling) and/or death may result
depending upon system water pressure changes and/or
supply water temperature changes. ASSE standard 1016,
1069 or 1070 listed devices should be used at fixtures to
prevent possible injury.
The Watts Hot Water Tempering Valves are designed to be
installed at or near the boiler or water heater. They are not
designed to compensate for system pressure fluctuations
and should not be used where ASSE standard 1016, 1069 or
1070 devices are required. These Watts valves should never
be used to provide “anti-scald” or “anti-chill” service.
The components of the system must be of materials with a
construction capable of withstanding the high limit output
temperatures of the water heating source.
!
WA R N I N G
Need for Periodic Inspection: Periodic inspection by a
licensed contractor is recommended. Corrosive water
conditions, temperatures over 210°F, and or unauthorized
adjustments or repair could render the valve ineffective
for service intended. Regular checking and cleaning of the
valve’s internal components and check stops helps assure
maximum life and proper product function. Frequency of
cleaning and inspection depends upon local water conditions and water temperature.
2
or 100 in 2 Diaphragm
Application Information n
Flowrite II 596MI Valves are used for mixing hot and cold-water
streams or bypassing flow with the valve in the return line. The
controlling instrument positions the mixing valve to obtain the
approximate mixture temperature.
Figure 1 shows an example of a mixing application, a typical
boiler hot water control system. The cold inlet supply is fed to
the upper inlet port (A port) of the valve as well as through the
boiler for production of hot water to be fed into the bottom port
(B port).
Figure 2 shows an example of a bypass application, piping for
control of a heating or cooling coil, with the valve in the return
line. The controlling instrument positions the valve so that the
hot water will bypass the coil when the air is at the proper temperature. A pump is recommended in the coil loop to improve
the heat transfer characteristics of the coil.
Coil
Bypass
Supply Supply
Stem down flow through coil.
Stem up flow through coil bypass.
Valve
Return
Figure 1
Cold Water
Supply
Boiler Hot Water Control System
Figure 2
Bypass
Coil
Stem up flow through coil.
Stem down flow through coil bypass.
Control
Valve
Return
A AB
B
Hot Water Inlet
Boiler
Valve
Return
Bypass Piping for Control of a Heating or Cooling Coil
Theory of Operation n
Air pressure from the controlling instrument enters the pressure
tight chamber of the actuator between the diaphragm and the
upper housing. An increase in control air pressure causes the
diaphragm to press down on the thrust plate, compressing the
springs and moving the valve stem downward. In the valve, this
reduces the flow through the "B" port and increases the flow
through the "A" port.
Conversely, A decrease in control air pressure reduces the
downward force on the actuator diaphragm, moving the
thrust plate and stem upward. The flow through the "B" port is
increased, and the flow through the "A" port is decreased.
Figure 3
A
B
Three-way valve
AB
In temperature mixing applications the hot inlet is usually
plumbed to the "A" side port, which will close on loss of signal.
Otherwise, the "B" lower port is used for hot, "A" upper side port
for cold, and the "AB" outlet for the mixed combination (see
Figure 3).
Three-way mixing valves are designed so that the flow from
either of the inlet ports to the outlet is approximately linear,
which means the total flow from the outlet is almost constant
over the stroke of the valve stem. See Figure-4 for typical flow
characteristics of 596 MI.
Figure 4
100%
90%
"A" Port
80%
70%
60%
50%
40%
Rated Flow
30%
20%
10%
0%
0%
20%
40%
StrokeStem In
60%
Rated Flow vs Stroke Diagram
2
"B" Port
80%
Stem Out
100%
Valve Sizing and Selection n
NOTE: Supply pressures (inlet) are affected by piping sched-
ule, internal surface conditions, and vertical runs (back pressure) so the actual flowing pressure is best measured at the
point of valve use.
Proportional to Mix Supply Flows
Proportional valves when used to blend two water flows control the output by varying the water temperature to the heat
exchanger at constant flow. These valves require high pressure drops for good control results. They can be sized for a
pressure drop of 20% of the flowing pressure or equal to 25% of
the pressure drop through the heat exchanger at full flow.
Table - 1 Water Capacity in Gallons Per Minute
Valve Cv
Size Rating Differential Pressure (∆ in psi)
5 10 15 20 25 30 35 40 45 50
2.5 74 165 234 287 331 370 405 438 468 496 523
3 101 226 319 391 452 505 553 598 638 678 714
4 170 380 538 658 760 850 931 1006 1075 1140 1202
5 290 648 917 1123 1297 1450 1588 1716 1834 1945 2051
6 390 872 1233 1510 1744 1950 2136 2307 2467 2616 2758
Proportional to Bypass Flow
Proportional mixing valves when used to bypass flow are piped
on the outlet side of the hot water source to throttle the water
flow and thereby control heat output. These valves are usually
selected to take a pressure drop up to 50% of the flowing pressure through the valve.
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