Watts CSM-91 8 Balancing Valve, Ductile Iron, Grooved

The Watts CSM-91 8 is an 8" manual circuit balancing valve with Grooved connections. It features a ductile iron body and a epdm seat. Rated to 375 psi and up to 230°F.

This 8 inch flow measurement valve monitors system flow in medium to high flow rate HVAC units, providing a highly accurate flow measurement. It consists of ductile iron body construction, pressure differential readout ports on both sides of the valve, two interchangeable brass metering ports and drain ports on both sides of the valve, two check valves with gasketed caps, bronze valve stem and plug disc, multi-turn adjustment handwheel, tamper-proof brass memory stop, positive shutoff and grooved end connections. It is ideal in water units such as pump packages and cooling towers.

Features

• Grooved connection
• Iron body construction
• Bronze valve stem
• Tamper proof brass memory stop
• Includes: Tamper Switch

Common Questions

Do I need a separate meter to read the flow?

Yes. The CSM-91 8 is a differential-pressure device: it meters through dual PT (pressure/temperature) ports with checked drip caps. You connect a balancing meter (or a differential gauge) across the two ports, read the pressure drop, and convert it to GPM using the Watts flow chart for the 8" body. The valve does not display flow on its own. If you want set-and-read balancing without a meter, use the Watts iDROSET CSD direct-reading series instead.

Can it also shut off the circuit?

Yes. The CSM-91 8 gives positive, drip-tight shutoff, so it doubles as the service valve for the circuit and you do not have to buy and install a separate ball valve next to it. The memory stop preserves your balanced setting: close the valve for service, reopen it against the stop, and the circuit returns to the same flow without rebalancing.

Can I use it on a domestic hot water recirculation line?

No. The CSM-91 8 is not a lead-free model, so it is restricted to closed hydronic heating and chilled-water loops and other non-potable service. For DHW recirculation balancing, choose the lead-free equivalent — the Watts LFCSM-61-S (PT-port) or LFiDROSET CSD (direct-reading).

Specifications

• Type: Balancing
• Size: 8"
• Inlet Size: 8"
• Outlet Size: 8"
• Connection: Grooved
• Body Material: Ductile Iron
• Seat / Seal Material: EPDM
• Max Pressure (psi): 375
• Application: Hydronic Heating/Cooling
• Country of Origin: United States
• Warranty: 1 Year Limited
• MPN: CSM-91 8
• Temperature: up to 230°F
• Lead-Free: No
• Balancing Type: Manual Circuit Balancing
• Valve Functions: Balancing;Flow Measurement;Shutoff
• Flow Readout: Dual PT ports, 1/4" SAE 45° flare, checked w/ drip caps
• Memory Stop: Yes
• Positive Shutoff: Yes