The Belimo Z2050QS-J is a 1/2 in. sweat, 2-way ZoneTight (QCV) zone valve body with a Cv of 5.9, 0% leakage and an equal percentage flow characteristic, sold without an actuator for use with Belimo CQB(X) non fail-safe or CQKB(X) electronic fail-safe actuators.
The ball valve closes off against 75 psi and handles chilled or hot water with up to 60% glycol from 36 to 212°F. The body is forged brass with a chrome plated brass ball and a 360 psi body pressure rating. The maximum Cv is set in the field with the actuator end stop clip, and the actuator snaps onto the valve without tools.
Best For
- Unit ventilators
- Fan coil units
- VAV reheat coils
- Fin tube casing
- Radiant panels
- Duct coils
- Closed water systems in large commercial buildings where higher close-off and the ability to change flow is needed
- Space-restricted installations
Warranty
Belimo warrants all ZoneTight valve and actuator components for 5 years from the date of production. If the water temperature exceeds the 212°F operating range because of a boiler control failure, the valve will safely contain the hot water but the manufacturer warranty becomes invalid.
ZOT Supply is an authorized Belimo distributor. Every Z2050QS-J ships as genuine Belimo product, with nationwide shipping.
Key Features
0% leakage ball valve
Belimo ball valve design with 0% leakage (A to AB), an equal percentage characteristic and a Cv of 5.9.
Field-adjustable maximum flow
The end stop clip changes the angle of rotation in 2.5° increments, setting the maximum Cv from 0.5 to 5.9.
Tool-free snap assembly
The actuator plugs onto the valve by hand, with the mounting orientation selectable in 180° increments.
75 psi close-off
Close-off pressure of 75 psi, 40 psi maximum differential pressure and a 360 psi body pressure rating.
Flow in either direction
Flow direction in both directions is possible; install upright to horizontal.
Two actuator families
Suitable actuators: CQB(X) non fail-safe and CQKB(X) electronic fail-safe.
Technical Specifications
Valve
| Valve model | Z2050QS-J |
| Valve type | ZoneTight (QCV) zone valve, 2-way, sweat |
| Cv (no end stop) | 5.9 |
| Nominal size | 1/2 in. [DN 15] |
| Pipe connection | Sweat |
| Flow pattern | 2-way |
| Flow characteristic | Equal percentage |
| Leakage rate | 0% |
| Fluid | Chilled or hot water, up to 60% glycol |
| Fluid temperature range (water) | 36...212°F [2...100°C] |
| Body pressure rating | 360 psi |
| Close-off pressure (Δps) | 75 psi |
| Differential pressure (Δpmax) | 40 psi |
| Operating range (angle of rotation) | 15...90° |
| Controllable flow range | 75° |
| Flow direction | Both directions possible |
| Installation orientation | Upright to horizontal (in relation to the spindle); not hanging with the stem pointing downwards |
| Valve body | Forged brass |
| Ball | Chrome plated brass |
| Stem | Brass |
| Stem seal | EPDM O-ring |
| Seat | PTFE, O-ring EPDM |
| O-ring | EPDM (lubricated) |
| Servicing | Maintenance-free |
| Valve weight | 0.35 lb [0.16 kg] |
| Suitable actuators, non fail-safe | CQB(X) |
| Suitable actuators, electronic fail-safe | CQKB(X) |
Maximum Cv by end stop clip position
| Clip position | 1 | 2 | 3 | 4 | 5 | 6 | N | No end stop |
|---|---|---|---|---|---|---|---|---|
| Max Cv | 0.5 | 0.7 | 1.2 | 1.7 | 2.4 | 3.4 | 4.8 | 5.9 |
| Runtime (s) | 30 | 37 | 43 | 49 | 55 | 62 | 68 | 75 |
Safety: California Proposition 65 warning, this product can expose you to chemicals including lead. Do not install the valve hanging with the stem pointing downwards.
Specifications per Belimo Z2050QS-J technical data sheet rev 2024-12-17, CQ/CQK Quick Mount manuals 71694-00001.K and 71775-00001.L, Belimo zone valve guide specification rev July 22, 2025. Reviewed 2026-09-23.
Documentation
FAQ
What is the Cv of the Belimo Z2050QS-J?
The Z2050QS-J has a Cv of 5.9 with no end stop. The end stop clip reduces the maximum Cv in steps down to 0.5 at clip position 1.
Which actuators fit the Belimo Z2050QS-J?
Belimo lists CQB(X) non fail-safe and CQKB(X) electronic fail-safe actuators as suitable for the Z2050QS-J. The actuator snaps on by hand without tools.
What is the close-off pressure of the Z2050QS-J?
The Z2050QS-J closes off against 75 psi, with a 40 psi maximum differential pressure and a 360 psi body pressure rating.
Can the Z2050QS-J be installed with the stem pointing down?
No. Install the valve upright to horizontal; it may not be installed hanging with the stem pointing downwards.
- Valve Pattern:
- 2-Way
- Valve Size:
- 1/2 Inch
- Connection Type:
- Sweat
- CV Rating:
- 5.9
- Actuator Type:
- Valve Only
