Caleffi 140340 DN15 Differential Pressure Regulating Valve

The 140340 is the DN 15 differential pressure regulating valve (DPCV) of the Caleffi 140 series, with a setting range of 5 to 30 kPa. It holds a constant pressure difference across a circuit zone, such as a riser or a bank of thermostatic valves, so that the two-way valves on the circuit control accurately without noise when the flow rate changes.

Constant pressure across a variable-flow zone

Systems with two-way thermostatic or modulating valves change flow all day. As the valves close, pressure across the zone rises and the remaining valves start to hiss or hunt. The datasheet describes the answer as a pair of devices: the 140 regulator keeps the differential pressure at the set value, and a 142 series shut-off and pre-regulation valve on the flow side sets the design flow rate for the zone. A capillary tube carries the flow-side pressure to the top of the diaphragm while the return pressure acts underneath, and the thrust on the obturator stem balances against the counter-spring at the set point.

Key features from the datasheet

• Suitable for zoned systems, rising columns, condensing-boiler systems, district heating and variable flow-rate systems with two-way valves
• Adjustable set point with a movable indicator and graduated scale in mbar on the knob
• Valve bodies and stems in dezincification-resistant alloy with a stainless-steel spring
• Shut-off with retention of the setting: an Allen wrench in the hole closes the circuit without changing the Dp setting
• Lead-sealing holes in the knob and body to prevent tampering
• Shell insulation supplied with the DN 15 to DN 40 sizes; the DN 50 is available without insulation

Technical specification

Selection and flow limits

Two setting ranges exist for each of six sizes, DN 15 to DN 50. The 1403 codes cover 5 to 30 kPa and the 1404 codes 25 to 60 kPa. The datasheet lists a minimum and a numerical maximum flow rate for each set point, so check that the design flow of the zone falls between them.

Derived: to correct a zone flow by a percentage, the datasheet equation Dp2 = (G2/G1)² × Dp1 applies; its worked example raises a 20 kPa setting to about 26.5 kPa for a 15 % flow increase.

Installation and commissioning notes

• Any installation position is allowed; on DN 15 to 25 the upper section can be turned about 45 degrees after loosening the locking nut so the capillary leaves in a convenient direction.
• Connect the capillary to the 142 series valve on the flow pipe; the optional manual accessory valve 538203 can isolate the circuit on DN 15 to 25.
• Commissioning order from the datasheet: system fully open, set the balancing valve to the design flow, measure the real circuit differential pressure, set the regulator to that value, then connect the capillary.
• For sizing the pump add the balancing valve loss, the circuit loss and the regulator loss; the datasheet example gives 3.5 + 20 + 3 = 26.5 kPa.
• If shut-off devices cannot be fitted, the built-in shut-off on the 140 and 142 valves isolates the zone and keeps the setting.

Applications in Gulf hydronic systems

Variable-primary chilled-water plants, district-cooling building interfaces, hotel and hospital risers and fan-coil systems in Oman and the GCC use two-way valves, which is exactly the duty the datasheet lists. A DN 15 regulator suits a small zone or a single branch; larger risers use DN 25 to DN 50. The datasheet quotes water and glycol mixtures only, so use outside that scope after confirming with the manufacturer.

Selection and installation notes

Hydronic components are selected from the design flow, the pressure drop and the maximum working pressure and temperature of the circuit. Check the connection size and thread type, fit isolating valves so the part can be serviced, flush the pipework before commissioning and respect the flow direction marked on the body. Insulate heating and chilled-water parts according to the project specification.

Information needed for a quotation

Send the full model code, the quantity, the delivery location in Oman or the GCC, the intended use and any accessories needed, so that the complete package can be quoted together.

Documents and supply information

The manufacturer data sheet is attached to this page and should be read together with the project specification and the site risk assessment before a purchase is confirmed. Ratings, standards and dimensions are quoted as printed on that sheet. Lead time, stock position and certificates available with the shipment are confirmed in the quotation, and we supply to Oman and the wider GCC region for industrial, utility and building services projects.

Accessories and related items

Frequently asked questions

What does the Caleffi 140340 do?

It keeps the differential pressure between flow and return of a circuit zone constant at a set value between 5 and 30 kPa, even when two-way valves change the flow.

Which valve is used with it?

The datasheet pairs it with a 142 series shut-off and pre-regulation valve on the flow pipe, connected by a 1.5 m capillary tube.

What are the pressure and temperature limits?

16 bar maximum working pressure, 6 bar maximum differential pressure on the diaphragm for DN 15 to 25, and -10 to 120 degrees C.

How accurate is the set point?

The datasheet states an accuracy of plus or minus 15 percent.

Who supplies the Caleffi 140340 in Oman?

Seven Star LLC is an independent supplier in Muscat and quotes against the exact code. Confirm size, setting range and the 142 partner valve before ordering.

Documents and quotation

The official Caleffi 140 and 142 series datasheet 01250/17 GB (2017) is linked on this page. Send the code, quantity and zone design data to request a quotation. See more in Hydraulic Valves & Components.