Hattersley 1934 PICV General Notes

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Pressure Independent Control Valve (PICV)
General Notes
The Hatterley Fig. 1934 PICV;
can be used in variable volume heating and
chilled water systems
provides modulating control for terminal units
when installed with a modulating actuator
at all pre-set flow rates with actuator
has built in Differential Pressure Control
has an operating temperature: 0 to 90˚C
has a maximum working P of 400kPa
has a maximum operating pressure of 25 bar
Integral test points for verification of P and
valve performance
PICV Fig. 1934
Installation and Operating Instructions
Page 2
Limits Of Use
These valves have been categorised in accordance with the Pressure Equipment Directive–PED.
The fluid to be transported is limited to group 2 liquids i.e. non-hazardous. On no account must these valves be used on any group 1 liquids, group 1 gases or group 2 gases.
Installation
These instructions are issued as guidelines only and do not cover all installed conditions. If unsure, please contact our Technical Helpline before installation.
Hattersley products are designed for installation and use within suitably
designed systems reflecting CIBSE, BSRIA and HVAC guidelines. Particular care should be taking with regards to;
- accessibility to valve for setting/adjustment
- tube cutting
- jointing
- bracketing/supports
orientation: whilst the PICV can operate correctly in different orientations,
there are recommendations regarding the orientation of actuators - Please refer to separate actuator IOM
would normally be installed on return pipework, i.e. after the equipment it is
controlling, but can be installed in flow if required.
ensure direction of flow is correct - indicated by cast arrow on body.
Fig. 1934 operates between a minimum and maximum pressure drop across
the valve - see commissioning.
PICV’s are not designed as isolation valves. Dedicated isolation valves
should be installed to isolate against system pressure, i.e. for maintenance etc., when disconnecting/draining pipework.
systems should be installed with strainers to protect the PICV and other
installed items.
Hattersley – Pressure Independent Control Valve – Fig. 1934
Installation and Operating Instructions
Page 3
Flushing
Control valves, like the PICV, are sized to give good control over the system flow, therefore have been designed with small convoluted flow paths. Even when fully open these flow paths may not allow adequate water velocities for flushing of the coil. In line with BSRIA recommendations, it is recommended that a flushing point be located between the coil and the PICV. This allows the coil to be flushed without the water passing through the PICV. As per the Hook-Up Elite Prime range.
Installation Cont.
Please note this valve must not be used for end of line service or as an isolation valve. In order for the valve to function as intended water quality should be maintained at all times (e.g. as per BSRIA BG50 or equivalent).
Set Position
The PICV set position can be established by
use of lookup table on page 5
Identify installed valve from marking
on side of body
Check flow rate required
Read across chart:
- Valve = DN15 SF
- Required flow rate = 0.15 l/sec
Set position = 6
To set the flow rate, using your hand, turn the dial to close the valve (position 0), then re-open the valve by turning the dial anti-clockwise until position 6 is reached. Please note at no point should any tools, such as spanners, be used to set the dial.
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Commissioning
The Fig. 1934 controls the flow rate depending on its set position, therefore, removing the need to measure the flow rate.
The Fig. 1934 maintains a constant differential pressure across its internal seat, any excess pressure being removed by the internal differential pressure controller.
To ensure that sufficient pressure is available for the differential pressure controller to control the flow rate correctly, a differential pressure reading should be taken using the test points provided.
When taking differential pressure readings, it is important that the system is running at full load, i.e. at their set position. This ensures that differential pressure readings are carried out in the most unfavourable conditions, guaranteeing optimum performance in normal running conditions.
To ensure that all PICVs are working at the required differential pressure, it is necessary to check the least favoured / index PICV. By verifying the least favoured PICV is set to the required differential pressure, all other PICVs must have a higher differential pressure. However, we would also recommend that a selection of other PICVs are tested along the circuit to verify this.
Hattersley – Pressure Independent Control Valve – Fig. 1934
Installation and Operating Instructions
Page 5
Differential Pressure Requirements
Each valve size DN15 at each % setting option requires a specific constant ΔP (Differential Pressure) to ensure the PICV is within its working range.
For flow rates in between settings, extrapolation of position can be used. The pump speed should be set to ensure that the required differential pressure
is always available. By setting the differential pressure across the least favoured PICV to the value stated in the above table, it ensures that minimum pump energy is used, therefore, reducing system running costs and CO2 emissions.
To set pump speed to achieve this; whilst measuring ΔP, increase pump speed until ΔP is at, or just above, the minimum shown in the table above. Flow rate verification should be carried out using separate Flow Measurement Devices (FMD) where fitted. In line with CIBSE & BSRIA recommendations, we recommend that as a minimum requirement, FMDs are installed in all branches.
Where flow rate verification is required at terminals, FMDs may also be installed at each terminal. Terminal flow rates can also be confirmed by measuring branch flow rates and closing individual terminal PICVs one at a time and measuring the reduction in flow at the branch. Care should be taken to ensure that reduced flow rates are still within the measuring range of the branch FMD, i.e. that the measured ‘signal’ doesn’t drop below 1kPa.
DN15 LF DN15 SF DN15 HF
POS
Typical
ΔP
FLOW POS
Typical
ΔP
FLOW POS
Typical
ΔP
FLOW
2 15 0.008 2 20 0.060 2 25 0.085 3 15 0.015 3 20 0.085 3 30 0.130 4 15 0.028 4 20 0.115 4 35 0.175 5 15 0.038 5 20 0.130 5 35 0.210 6 20 0.050 6 20 0.150 6 35 0.250 7 20 0.060 7 20 0.170 7 40 0.280 8 20 0.070 8 25 0.180 8 45 0.300 9 20 0.075 9 25 0.190 9 45 0.320
10 20 0.080 10 25 0.200 10 50 0.340
Installation and Operating Instructions
Hattersley – Pressure Independent Control Valve – Fig. 1934
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H_PICV_FIG. 1934_0818
IOM_HNH002941
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systems in accordance with BS EN ISO 9001:2008
FM311 ISO 9001
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