Basic Documentation
Table Of Contents
- This is supplemental language for a spec. This is not an all inclusive spec. This is language that is meant to be copied and pasted into an existing spec.
- PART 1 - GENERAL
- PART 2 - PRODUCTS
- 2.1 PRESSURE INDEPENDENT CONTROL VALVES (PICV)
- A. General
- 1. All control valves shall be sized by the control vendor. All control valve bodies shall be suitable for the static and dynamic pressures of the system. Control valve operators shall be sized to close against a differential pressure equal to the d...
- 2. The valve seat differential pressure rating shall exceed the pump dynamic head design pressure.
- 3. All automatic control valves controlled by the BAS shall be furnished by the controls contractor unless otherwise noted in these documents.
- 4. All automatic control valves shall be installed by the mechanical trade.
- 5. The controls contractor shall provide wiring as follows:
- a. All line voltage power for electric valve actuators shall be wired by the controls contractor from the nearest available power panel. Coordinate with electrical trade.
- b. All low voltage wiring between the controller and the valve actuator shall be wired by the controls contractor.
- c. All wiring between safeties and the valve actuator shall be wired by the controls contractor.
- d. All wiring shall comply with code requirements. Segregate high and low voltage wiring and circuits and segregate the Fire Alarm (FACS) and BAS controls wiring.
- B. Manufacturer
- C. Where to use PICVs
- 1. Provide PICVs where called for in the specifications, sequences of operations, or on the drawings.
- 2. If it is not stated elsewhere, PICV valves should be provided to meet the following guidelines:
- a. Provide in direct return, constant speed pumping systems.
- b. Provide in direct return, variable flow water systems where with the system at full flow the pressure differential between the supply connection and the return connection is more than double the pressure drop of the circuit or loop at design flow (...
- c. Provide in reverse return, constant speed pumping systems where the circuits and loop pressure drops differ by more than 50%.
- d. Provide in reverse return, variable speed pumping systems where the differential pressure between the systems will vary more than the pressure drop of the circuit or loop.
- e. Provide in systems that have direct return headers and reverse return branch lines where with the system at full flow the pressure differential between the supply connection and the return connection is more than double the pressure drop of the bra...
- D. Piping for circuits with PICVs
- 1. Systems installed with PICVs shall not require balancing valves.
- 2. Calibrated balancing valves shall not be required in branches or loops where PICV are installed.
- 3. Automatic flow control valves are strictly prohibited in branches or loops where PICVs are installed.
- 4. Circuit setters may be required for coils with multiple sections. Follow the piping details.
- 5. Install pressure ports on either side of the coil for the balancer to test the flow across the coil at different system flows.
- E. Sizing Criteria (Pressure Independent):
- 1. Two-way modulating service:
- a. Determine the design GPM of the actual coil that is selected be used (may be different than the coil and GPM on the design coil schedule).
- b. Select the PICV valve with a GPM rating higher than the GPM required.
- c. If more than one valve fits the GPM rating, then pick the valve that matches or is closest to the line size of the circuit piping.
- d. If the maximum GPM of the valve exceeds the design GPM required, then adjust the Flow Limiter setting on the valve to the GPM required plus 10%.
- e. Traditional flow coefficient and pressure drop sizing is not applicable to PICV valves.
- 1. Two-way modulating service:
- F. Flanged Valves, line size 2 ½” and larger
- 1. Controlled Media Specific Items
- a. The control valve shall be suitable for chilled water to a minimum of 34 F (1 C) and hot water to a maximum temperature of 248 F (120 C).
- b. The control valve shall be suitable for up to 50% ethylene or propylene glycol solutions, chilled glycol/water solutions to a minimum of 34 F (1 C) and hot glycol/water solutions to a maximum temperature of 248 F (120 C).
- 2. General Construction Materials/Applicable
- a. Control valve bodies shall be constructed of cast iron and shall meet requirements of ANSI 125 or ANSI 250 pressure classes.
- b. Inlets and outlets shall be clearly marked on the valve bodies.
- c. Valves shall be constructed with a single chamber and multiple seats to provide flow limiting, pressure compensation and flow control.
- d. Valves shall contain a mechanical, spring-loaded pressure independent regulator to maintain a consistent differential pressure across the control port of the valve.
- e. Valves shall contain an actuated flow control portion that responds to the modulating signal from the controller. This control valve portion shall have a linear flow characteristic.
- f. Valves shall contain a field adjustable flow limiter. The flow limiter shall be easily adjustable in the field without the use of special tools. The adjustment dial shall be set for and indicate maximum flow. It shall be possible to manually lim...
- 1) A table shall be attached to each valve indicating GPM corresponding to each setting on the dial.
- 2) No mechanical devices besides the valve and actuator shall be permitted to adjust the maximum flow setting. Flow limiting port shall be integrated into the valve body.
- 3) The valve shall always maintain full nominal stroke regardless of the maximum flow setting of the flow limiter.
- 4) The flow limiter shall be lockable and tamper resistant when the actuator is installed correctly.
- g. At any given actuator setting the flow accuracy across the entire pressure independent operating range of the automatic differential pressure regulator shall be ±10% or less.
- h. Pressure ports shall be standard in the body of the valve for all flanged valves. Pressure ports shall provide a means for a balancer to test the differential pressure across the valve control port to ensure the PICV is operating within the pressu...
- i. Valves 2-1/2 inch and larger shall be provided with ANSI 125 or ANSI 250 flanged connections.
- j. Valves 2-1/2 inch and larger line size shall meet or exceed ANSI Class IV (0 to 0.01% of nominal maximum) leakage rating at 100 psi close off.
- k. The differential pressure range for effective pressure independent operation shall be 3.6 – 90 psi or 8 – 90 psi for 2-½ and 3 inch flanged valves depending on the maximum gpm flow range of the valve.
- l. Valve materials shall meet or exceed the following:
- 1. Controlled Media Specific Items
- G. Threaded Valves, line size ½” to 2”
- 1. Controlled Media Specific Items
- a. The control valve shall be suitable for chilled water to a minimum of 35 F (2 C) and hot water to a maximum temperature of 250 F (121 C).
- b. The control valve shall be suitable for up to 50% ethylene or propylene glycol solutions, chilled glycol/water solutions to a minimum of 35 F (2 C) and hot glycol/water solutions to a maximum temperature of 250 F (121 C).
- 2. General Construction Materials/Applicable Standards
- a. Control valve bodies shall be constructed of forged DZR brass and shall meet requirements of ANSI 250 pressure class.
- b. Inlets and outlets shall be clearly marked on the valve bodies.
- c. Valves shall be constructed with a single chamber and multiple seats to provide flow limiting, pressure compensation and flow control.
- d. Valves shall contain a mechanical, spring-loaded pressure independent regulator to maintain a consistent differential pressure across the control port of the valve.
- e. Valves shall contain an actuated flow control portion that responds to the modulating signal from the controller. This control valve portion shall have a linear flow characteristic.
- f. Valves shall contain a field adjustable flow limiter. The flow limiter shall be easily adjustable in the field without the use of special tools. The adjustment dial shall be set for and indicate maximum flow. It shall be possible to manually lim...
- 1) The dial shall show settings in GPM.
- 2) No mechanical devices besides the valve and actuator shall be permitted to adjust the maximum flow setting. Flow limiting port shall be integrated into the valve body.
- 3) The valve shall always maintain full nominal stroke regardless of the maximum flow setting of the flow limiter.
- 4) The flow limiter shall be lockable and tamper resistant when the actuator is installed correctly.
- g. At any given actuator setting the flow accuracy across the entire pressure independent operating range of the automatic differential pressure regulator shall be ±10% or less.
- h. Pressure ports shall be an optional accessory that can be added to threaded valves. Pressure ports shall provide a means for a balancer to test the differential pressure across the valve control port to ensure the PICV is operating within the pres...
- i. Valves 2 inch and smaller shall be provided female NPT piping connections.
- j. Close-off and leakage
- 1) Normally open valves ¾ inch and smaller line size shall meet or exceed ANSI Class IV (0 to 0.01% of nominal maximum) leakage rating at 200 psi close off.
- 2) Normally closed valves 1-1/4 inch and smaller line size shall meet or exceed ANSI Class IV (0 to 0.01% of nominal maximum) leakage rating at 45 psi close off.
- 3) Valves 1-1/2 and 2 inch line sizes shall meet or exceed ANSI Class III (0 to 0.1% of nominal maximum) leakage rating at 50 psi close off.
- k. Differential pressure ranges:
- 1) The start-up differential pressure of the automatic differential pressure regulator shall be between 2.3 and 4.6 psi, depending on valve size and flow rate for ½ to 2 inch valves.
- 2) The maximum operating differential pressure of the automatic differential pressure regulator shall be 58 psi for ½ to 2 inch valves.
- 3) In no instance shall the minimum effective pressure differential for effective pressure independent operation exceed 4.6 psi for valves less than or equal to 2 inch line size.
- l. Valve materials shall meet or exceed the following:
- 1. Controlled Media Specific Items
- H. Actuators - Electric
- 1. The valves shall be provided with an actuator by the same manufacturer, factory installed.
- 2. All actuators shall have visual position indication.
- 3. No external programming device shall be required.
- 4. Actuator shall be electric motor driving, microprocessor signal controlled.
- 5. Modulating valves shall be positive positioning, responding to a 0-10VDC, 2-10VDC or 4-20mA signal. Floating modulating signals are acceptable for modulation on terminal units and radiation units. There shall be a visual valve position indicator.
- 6. Power: All actuators shall be 24VAC power and less than 100VA draw. Power shall be via Class 2 wiring. Actuators requiring more than 100VA shall have a dedicated conduit for power wiring, not mixed with the signal wiring.
- 7. Fail Safe: Valves actuators shall position the valve in a fail-safe position when the power supply is disrupted or the signal goes to 0. Fail-safe according to the following guidelines unless otherwise stated in the sequence of operations
- a. Power fail safe shall be via spring loaded mechanical means
- b. Any AHU hot water exposed to ventilation air shall fail open
- c. AHU Chilled water coils exposed to ventilation air in possible freezing conditions shall be fail open
- d. AHU Chilled water coils that are drained in winter months or are in climate zones without freezing conditions shall be fail-in-place
- e. Terminal unit valves shall fail-in-place
- f. Chiller isolation valves shall fail-in-place
- g. Boiler isolation valves shall fail-in-place
- h. Any steam supply serving a water heat exchanger shall fail closed
- i. Any steam supply to a terminal unit coil or a coil without ventilation air shall fail closed.
- j. Any steam coil exposed to ventilation air shall fail open
- 8. Fail in Safe valves on primary equipment such as chilled water systems, hot water systems and condenser water systems shall have a means to manually open the valve when power is not available, such as a hand wheel or a geared crank with a clutch.
- 9. The actuator shall be designed with a current limiting motor protection. A release button (clutch) or handle on the actuator shall be provided to allow for manual override (except when actuator is spring return type).
- 10. Actuator shall provide minimum torque required for proper valve close-off. The close-off differential pressure rating of the valve shall exceed the highest possible head pressure available at the pump plus 10%, and still be rated for a Class IV l...
- 11. The actuator shall have the capability of adding auxiliary switches or feedback potentiometer if specified.
- 12. All automatic control valves installed in locations exposed to the elements shall be provided with weather resistant housings and heaters for climates that reach below freezing.
- 13. Actuators shall be UL and CSA listed.
- Add this section to the Balancing Specification:
- A. General
- 2.2 Balancing for circuits with Pressure Independent Control Valves
- A. If balancing valves are installed, open them 100% and lock them in place.
- B. Test the differential pressure across the valve control port to ensure the PICV is operating within the pressure independent range.
- C. Stoke the PICV valve to full open. Test the GPM across the coil. Run the system pump at the high and lowest anticipated system pump flows. Make sure the coil GPM is attainable in all flow conditions. If not, then increase the flow limiter on th...
- 2.1 PRESSURE INDEPENDENT CONTROL VALVES (PICV)
Project Name 230900 - 6 BAS AND CONTROL FOR HVAC
Date
A. If balancing valves are installed, open them 100% and lock them in place.
B. Test the differential pressure across the valve control port to ensure the PICV is operating
within the pressure independent range.
C. Stoke the PICV valve to full open. Test the GPM across the coil. Run the system pump at the
high and lowest anticipated system pump flows. Make sure the coil GPM is attainable in all
flow conditions. If not, then increase the flow limiter on the PICV valve in steps until design
flow to the coil is reached.