The Belimo Z2050QPF-F+CQKB24-SR-RL is a 2-way, 1/2″ press fit ZoneTight (QCV) zone valve with a Cv of 1.4, supplied as an assembly with the Belimo CQKB24-SR-RL electronic fail-safe 2-10 VDC modulating actuator powered at 24 VAC/DC. The valve is rated for 75 psi close-off with 0% leakage and an equal percentage flow characteristic.
The wiring diagram shows 2 VDC = closed and 10 VDC = open; on loss of power the actuator drives the valve to its open fail position.
Specifications on this page are taken from the Belimo Z2050QPF-F+CQKB24-SR-RL assembly technical data sheet (actuator section rev 2024-06-27), the Belimo Z2050QPF-F valve technical data sheet (rev 2026-02-07) and Belimo Quick Mount Visual Instruction Manual 71694-00001.K. Verified 2026-09-11.
Press fit hydronic piping in space restricted locations where the actuator must mount without tools. Belimo lists unit ventilators, fan coil units, VAV reheat coils, fin tube casing, radiant panels and duct coils as common QCV applications in large commercial buildings.
Warranty
Belimo warrants all components of the ZoneTight valve and actuator assembly for 5 years from the date of production. Operating the valve above 212°F voids the manufacturer warranty.
Key Features
75 psi Close-Off, 0% Leakage
Ball valve with a 75 psi close-off rating, 40 psi maximum differential pressure and an equal percentage flow characteristic.
Field Adjustable Cv
An end stop clip limits rotation in 2.5° increments to set maximum flow, from Cv 0.1 up to the full 1.4. Modulating actuators must re-adapt after the clip is moved.
Tool-Free Snap Assembly
The actuator plugs onto the valve by hand with vertical movement only, and can be oriented in 180° increments.
Electronic Fail-Safe, Fails Open
Drives the valve open on loss of power. Bridging time 2 s, pre-charging time 5 to 20 s, fail-safe running time <60 s.
Modulating with Feedback
Operating range 2 to 10 V, 4 to 20 mA with the ZG-R01 500 Ω resistor, and 2 to 10 V position feedback.
Plenum Rated
UL 2043 compliant; suitable for use in air plenums per Section 300.22(C) of the NEC and Section 602 of the IMC.
Technical Specifications
Valve Body (Z2050QPF-F)
| Valve pattern | 2-way |
| Valve size | 1/2″ [DN 15] |
| Cv | 1.4 |
| Pipe connection | Press fit |
| Fluid | chilled or hot water, up to 60% glycol |
| Fluid temperature range | 36 to 212°F [2 to 100°C] |
| Body pressure rating | 250 psi |
| Close-off pressure | 75 psi |
| Differential pressure max | 40 psi |
| Flow characteristic | equal percentage |
| Leakage rate | 0% |
| Controllable flow range | 75° |
| Angle of rotation | Operating range 15 to 90° |
| Direction of rotation | opens counterclockwise, closes clockwise |
| Flow direction | both directions possible |
| Installation orientation | upright to horizontal (in relation to the stem); not hanging with the stem pointing down |
| Servicing | maintenance-free |
| Valve body material | forged brass |
| Ball | chrome plated brass |
| Stem | brass |
| Stem seal | EPDM O-ring |
| Seat | PTFE, O-ring EPDM |
| Valve body weight | 0.48 lb [0.22 kg] |
| Dimensions | A 4.9″ [125 mm], B 4.2″ [107 mm], E 0.9″ [24 mm], F 0.9″ [24 mm]. Height C is 3.1″ [80 mm] or 3.3″ [83 mm] and D is 2.6″ [65 mm] or 2.7″ [69 mm], per the two actuator housings drawn on the data sheet |
Valve body weight is the current Z2050QPF-F technical data sheet rev 2026-02-07 figure. The valve section of the Z2050QPF-F+CQKB24-SR-RL assembly sheet (rev 2024-06-12) lists 0.33 lb [0.15 kg].
Belimo states this product can expose you to lead, a chemical known to the State of California to cause cancer and reproductive harm (Proposition 65).
Actuator (CQKB24-SR-RL)
| Actuator type | Electronic Fail-Safe, modulating |
| Nominal voltage | AC/DC 24 V |
| Nominal voltage frequency | 50/60 Hz |
| Nominal voltage range | AC 19.2 to 28.8 V / DC 21.6 to 28.8 V |
| Power consumption in operation | 2.5 W |
| Power consumption in rest position | 0.5 W |
| Transformer sizing | 5 VA |
| Electrical connection | 22 GA plenum cable, 3 ft [1 m], with 1/2″ NPT conduit connector |
| Operating range Y | 2 to 10 V |
| Operating range Y note | 4 to 20 mA w/ ZG-R01 (500 Ω, 1/4 W resistor) |
| Position feedback U | 2 to 10 V |
| Control direction (wiring diagram) | 2 VDC = Closed, 10 VDC = Open |
| Fail position | Open |
| Bridging time | 2 s |
| Pre-charging time | 5 to 20 s |
| Angle of rotation | 90°, adjustable with mechanical stop |
| Running time (motor) | 75 s / 90° |
| Running time fail-safe | <60 s |
| Noise level, motor | 35 dB(A) |
| Position indication | pointer |
| Degree of protection IEC/EN | IP40 |
| Degree of protection NEMA/UL | NEMA 2 |
| Enclosure | UL Enclosure Type 2 |
| Agency listing | cULus acc. to UL60730-1A/-2-14, CAN/CSA E60730-1:02; CE acc. to 2014/30/EU and 2014/35/EU |
| Quality standard | ISO 9001 |
| UL 2043 | Suitable for use in air plenums per Section 300.22(C) of the NEC and Section 602 of the IMC |
| Ambient humidity | Max. 95% RH, non-condensing |
| Ambient temperature | 35 to 104°F [2 to 40°C] |
| Storage temperature | -40 to 176°F [-40 to 80°C] |
| Housing material | UL94-5VA |
| Actuator weight | 0.55 lb [0.25 kg] |
Field Flow Setting (End Stop Clip)
| Clip position | Cv (V'max) |
|---|---|
| 1 | 0.1 |
| 3- | 0.2 |
| 4+ | 0.4 |
| 5+ | 0.6 |
| 6 | 0.8 |
| N | 1.2 |
| No end stop | 1.4 |
Clip values are from the Z2050Q(S)(PF)-F row of Belimo Quick Mount Visual Instruction Manual 71694-00001.K. CQK manual 71775-00001.L prints the same row as Z2050Q(S)-F without the PF designation.
Documentation
Related Products
Belimo Z2050QPF-F+CQKB24-SR-LL (electronic fail-safe, 24 VAC/DC, Fails Open)
Belimo Z2050QPF-F+CQKB24-SR-LR (electronic fail-safe, 24 VAC/DC, Fails Closed)
Belimo Z2050QPF-F+CQKB24-SR-RR (electronic fail-safe, 24 VAC/DC, Fails Closed)
Belimo Z2050QPF-F+CQKCB24-SR-RR (electronic fail-safe, 24 VAC, 2 VDC = Open)
Frequently Asked Questions
What is the Belimo Z2050QPF-F+CQKB24-SR-RL?
It is a Belimo Z2050QPF-F 2-way, 1/2″ press fit ZoneTight zone valve (Cv 1.4) supplied with the CQKB24-SR-RL electronic fail-safe actuator, 24 VAC/DC, 2-10 VDC modulating control.
What are the pressure ratings of the Z2050QPF-F+CQKB24-SR-RL?
Belimo publishes a 250 psi body pressure rating, 75 psi close-off pressure and a 40 psi maximum differential pressure, with 0% leakage.
Does 2 VDC open or close the Z2050QPF-F+CQKB24-SR-RL?
The wiring diagram on the CQKB24-SR-RL data sheet shows 2 VDC = closed and 10 VDC = open.
What happens to the Z2050QPF-F+CQKB24-SR-RL on power loss?
The electronic fail-safe actuator drives the valve open. Fail-safe running time is <60 s after a bridging time of 2 s.
Can the maximum flow of the Z2050QPF-F+CQKB24-SR-RL be reduced in the field?
Yes. Moving the end stop clip sets the maximum Cv between 0.1 at position 1 and 1.2 at position N, or 1.4 with no end stop. Trigger an adaptation on the modulating actuator after every change.
Belimo warrants all components of the ZoneTight valve and actuator assembly for 5 years from the date of production. Warranty terms are stated in the Belimo Zone Valve Guide Specifications (rev. July 22, 2025). Operating the valve above its 212°F fluid temperature rating voids the manufacturer warranty.
- Valve Pattern:
- 2-Way
- Valve Size:
- 1/2 Inch
- Connection Type:
- Press Fit
- CV Rating:
- 1.4
- Actuator Type:
- Fail-Safe
- Voltage:
- 24VAC/DC
- Control Signal:
- 2-10VDC
- Auxillary Switch:
- None
