PICCV Application

PICCV Application
M40019 - 06/10 - Subject to change. © Belimo Aircontrols (USA), Inc.
Belimo PICCV Flow Verification & Commissioning
This document details the flow verification and commissioning
procedures for PICCV (pressure independent characterized control
valves). The flow verification techniques contained within this
document are optional and at the discretion of the Mechanical
Engineer/Designer. These procedures are not mandatory to ensure
proper operation of PICCV valves. Pressure independent control valves
are very different than a pressure dependent control valve. Pressure
variations in the system will not affect flow through the valve. The
ability to adjust and/or control the flow rate which passes through the
PI valve is not possible via another mechanical device and additional
mechanical devices should not be used. This makes the TAB/
Commissioning process much different than with standard control
valves. Pressure independent valves offer numerous maximum design
flow values in each valve body size. It is important to note that most
pressure independent valves will not travel a full 90 degrees of rotation
when commanded to full design flow position. Design flow in a PICCV
is adjusted through the maximum angle of ball travel. Therefore, if the
valve’s maximum flow setting is not at the end of the range, the valve
will travel to a point less than 90 degrees. This is normal operation for
pressure independent control valves.
Note to Mechanical Designer/Owner: It is essential that the mechanical
contractor install three (3) independent pressure/temperature ports if
the PICCV is not supplied with integrated ports. Please refer to Figure
A contained in this document for P/T port locations. External P/T ports
allow for true independent verification of proper PICCV operation.
Additionally, the external P/T ports allow for future comprehensive
troubleshooting and diagnosis once the system has been in operation
for an extended time period.
For proper and accurate flow verification of the PICCV, it is essential
that the mechanical contractor install two (2) separate independent
pressure/temperature ports (P/Ts) if the PICCV valve body is supplied
with integrated ports. (See Figure A -the integrated P/T port labeled 3b
performs the same function as P/T port 3a).
I. P/T port #1 and P/T port #2 are used for measuring pressure
differential across the coil (used to measure water pressure drop to
equate to flow or to measure water temperature delta T through the
coil).
II. P/T port #2 and P/T port #3a (or #3b if integrated into valve body)
are used to measure pressure drop across the PICCV (must be
between 5-50 psi pressure across valve body). Pressure Independent
valve body must have required differential pressure within this range
WITH VALVE ASSEMBLY COMMANDED TO DESIGN FLOW. Valve
shall be commanded to design flow position via EMS signal. Do not
manually open the valve with override handle. This pressure difference
across the PICCV is necessary to ensure the valve is working pressure
independently.
Pre Flow Verification System Checklist
In order to ensure a properly functioning hydronic system utilizing
Pressure Independent Characterizing Control Valves, the mechanical
contractor and/or T&B professional must verify that the following items
have been confirmed before beginning flow verification.
Each flow verification / commissioning procedure presented in this
document begins with a reference to the checklist contained below.
This serves as a constant reminder to the flow verification professional
that these parameters must be met so that proper flow results can be
measured / obtained.
*Items to check before beginning flow verification procedure:
• Verify that System is purged of air and filled to proper pressure.
• Verify that each PICCV valve has at least 5 psi but less than
50 psi dP across the valve (fig. A) by following one of the following
two measurement options:
− Reading taken across P/T ports 2 & 3a
− Reading taken across P/T port 2
• Verify Proper pump operation per manufacturers specifications.
• Verify proper supply water temperature is available and is at design
temperature.
• Proper Air filter maintenance has been completed.
• Fan belts are in proper working order.
• Heat transfer devices (coils) are clean.
• Strainers are clean.
• All manual shutoff valves are open.
Figure A
2
3a
(Optional)
1
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Belimo PICCV Flow Verification & Commissioning
All bypass valves are closed.
No automatic or manual balancing valves exist (or if they do, they
must be set fully open and locked so as not to interfere with the
pressure independency of the PICCV).
Below are the accepted procedures for verifying/commissioning
pressure independent control valves.
Procedure #1 (System Verification) – Total System
Flow Method
Verification for PICCV Cooling Valves/Heating Valves
1. Verify that System is in proper working order. *See Items to check
before beginning flow verification procedure contained at the
beginning of this document.
2. Command open all PICCVs in a given system via the building
automation system if the total connected load matches the pump
capacity and system diversity = 100%. Systems with less than
100% diversity need to have a % of valves closed to match pump
capacity.
3. Ensure that pumps are commanded to 100% speed (or VFD control
loop has high enough dP setpoint to satisfy connected load).
4. Verify total system flow is at system design flow rate via accurate
method:
Calibrated Circuit Setter on main lines
Orifice
Venturi
Ultrasonic Flowmeter
5. Decrease the pump speed (or decrease dP setpoint if under control)
until a measureable flow decrease occurs.
6. Increase pump speed (or increase dP setpoint if under control)
slowly until design flow is reestablished. Make note of this final
measured dP. This will be the correct system dP operating setpoint.
NOTE: If total flow does not match design flow then
troubleshooting must be done to determine cause. This may
involve verifying flows at the terminal level.
Procedure #3 (Terminal Level Verification) – Water
DeltaT Method
Verification for PICCV Cooling Valves/Heating Valves
1. Verify that System is in proper working order. *See Items to check
before beginning flow verification procedure contained at the
beginning of this document.
2. Ensure that water is at design temperature.
3. Ensure that terminal airflow is at design flow rate (cfm).
4. Command open pressure independent characterized control valve to
maximum design flow position.
5. Reference approved engineering document containing design water
deltaT for heating/cooling coil associated with corresponding
pressure independent characterized control valve.
6. Measure water temperature differential of coil by using P/T ports #1
and #2 as referenced in Figure A.
7. Measured temperature differential should be equal to designed
water temperature differential.
Procedure #4 (Terminal Level Verification) – Coil dP
(DeltaP) Method
Verification for PICCV Cooling Valves and PICCV Heating Valves
1. Verify that System is in proper working order. *See Items to check
before beginning flow verification procedure contained at the
beginning of this document.
2. Command open pressure independent characterized control valve to
maximum design flow position.
3. Reference approved engineering document containing design coil
water pressure drop (usually expressed in ft. of H2O) for
design flow. This value will be for the heating/cooling coil associated
with corresponding pressure independent characterized control
valve.
4. Measure coil dP by using P/T ports #1 & #2 as referenced in Fig. A.
5. Formula to calculate flow is:
Actual GPM = √(Measured Coil dP/Design Coil dP) x Design GPM
Note: Coil dP and Design dP expressed in feet of H2O.
Procedure #2 (Terminal Level Verification) –
Air DeltaT Method
Verification for PICCV Cooling Valves/Heating Valves
1. Verify that System is in proper working order. *See Items to check
before beginning flow verification procedure contained at the
beginning of this document.
2. Ensure that water is at design temperature.
3. Ensure that terminal airflow is at design airflow rate (cfm).
4. Command open pressure independent characterized control valve to
maximum design flow position
5. Reference approved engineering document containing design air
delta T for heating/cooling coil associated with corresponding
pressure independent characterized control valve.
6. Measure coil inlet air temperature and coil discharge air
temperature.
7. Difference between coil inlet air reading and coil discharge air
reading should equal or exceed design air delta T.
800-543-9038 USA
16
866-805-7089 CANADA
203-791-8396 LATIN AMERICA
M40019 - 06/10 - Subject to change. © Belimo Aircontrols (USA), Inc.
•
•
Belimo PICCV Flow Verification & Commissioning
M40019 - 06/10 - Subject to change. © Belimo Aircontrols (USA), Inc.
Field adjustment of maximum flow and /or flow accuracy.
(This function is not a requirement. This procedure is purely optional
and is not a mandatory procedure for proper operation of PICCV
valves.)
Flow Accuracy of the PICCV valve body is +/-10%. However, actuator
hysteresis and installation can have an effect on measured accuracy of
the PICCV assembly (actuator/valve) in the field. The accuracy of the
PICCV assembly can be improved in the application.
The maximum flow setting and/or flow accuracy can be adjusted in the
field using the Belimo PC-Tool or ZTH-PICCV (shown on next page).
Please contact your local Belimo representative to obtain/purchase this
tool or arrange to have a Belimo representative visit the project site to
make adjustments.
For additional information pertaining to the flow verification and
commissioning industry, please visit the website of these organizations
that promote the certification and continuing education of industry
professionals in the Test and Balance discipline.
NEBB - National Environmental Balancing Bureau, http://www.nebb.org/
TABB - Testing Adjusting Balancing Bureau, http://www.tabbcertified.org/
800-543-9038 USA
866-805-7089 CANADA
203-791-8396 LATIN AMERICA
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