Spirax Sarco DP27 maintenance kits are genuine factory-packed sets of spares designed for the routine maintenance of DP27 and DP27R pilot operated pressure reducing valves. It is recommended that the valve is dismantled once every twelve to eighteen months for a complete overhaul, ideally carried out with the valve removed from the line. Genuine Spirax Sarco replacement parts ensure the continued safe and stable operation of the pressure reducing station.

Maintenance Kit Contents

Each maintenance kit is a stand-by set of spares covering all items required for routine maintenance of the DP27 / DP27R pressure reducing valve. When ordering, always state the size and type of the valve (e.g., Maintenance kit for a Spirax Sarco DN25 DP27).

Kit contents	Item
Main diaphragm (2 off)	A
Pilot diaphragm (2 off)	B
Pilot valve assembly (with integral seal)	C or C1
Internal strainer screen	M
Main valve return spring	N
Downstream pressure balance pipe assembly (internal pressure sensing pipe)	Q
Body gasket (3 off)	R

Interchangeability of Spares

The following table shows how in certain sizes some parts are interchangeable. For example, in the line headed 'Main diaphragm', the diaphragm used in the screwed valves 1/2" and 3/4" is common to these sizes by the letter 'a'; the letter 'c' indicates that one diaphragm is common to the DN40 and DN50 valves.

Part	Screwed 1/2"LC	Screwed 1/2"	Screwed 3/4"	Screwed 1"	Flanged 15LC	Flanged 15	Flanged 20	Flanged 25	Flanged 32	Flanged 40	Flanged 50
Maintenance kit	a	a	a	b	f	f	a	b	c	d	e
Main diaphragm	a	a	a	b	a	a	a	b	b	c	c
Pilot diaphragms	a	a	a	a	a	a	a	a	a	a	a
Pilot valve assembly	a	a	a	a	a	a	a	a	a	b	b
Pilot filter element	a	a	a	a	a	a	a	a	a	a	a
Main valve assembly	a	b	c	d	a	b	c	d	e	f	g
Internal strainer screen	a	a	a	b	f	f	a	b	c	d	e
Main valve return spring	a	a	a	a	a	a	a	a	a	c	c
Pressure adjustment spring	a	a	a	a	a	a	a	a	a	a	a
Control pipe assembly	a	a	a	b	f	f	a	b	c	d	e
Balance pipe assembly	a	a	a	b	f	f	a	b	c	d	e
Body gasket	a	a	a	a	a	a	a	a	a	b	b
Pushrod and main diaphragm plate	a	a	a	b	a	a	a	b	b	c	c

Maintenance and Replacement Procedures

WARNING

Handling precautions for PTFE: Within its working temperature range PTFE is a completely inert material, but when heated to its sintering temperature it gives rise to gaseous decomposition products or fumes which can produce unpleasant effects if inhaled. Smoking should be prohibited in workshops where PTFE is handled because tobacco contaminated with PTFE will during burning give rise to polymer fumes.

DANGER

The body gasket (all DP27 derivatives) and actuating chamber gasket (DP27R) contains a thin stainless steel support ring which may cause physical injury if not handled and disposed of correctly. Always isolate the reducing valve and zero the pressure before actioning any maintenance programme.

How to renew the pilot filter element

1. Isolate the reducing valve and zero the pressure.
2. Unscrew the filter cap and carefully withdraw the filter element.
3. Replace the element and tighten the filter cap to 90 - 100 N m. Note: The gasket is re-usable.

How to renew the pilot valve assembly

1. Isolate the reducing valve and zero the pressure.
2. Unscrew the 4 off spring housing securing nuts and remove spring housing, bottom spring plate and diaphragms (For DP27R, remove the air control block).
3. Unscrew and remove the pilot valve assembly (19 mm A/F). The pilot assembly has an integral PTFE seal.
4. Apply superlube grease to the threads before screwing the new pilot valve into the housing. Torque 45 - 50 N m.
5. Check that there is a very slight clearance between the top of the plunger and a straight edge placed across the diaphragm location recess.
6. Refit the two diaphragms making sure that they are fitted the same way round as they were removed and that all contact faces are clean.
7. Assemble the spring housing and tighten the nuts to the recommended torques (M10: 40-50 N m; M12: 45-55 N m).

How to renew or clean main diaphragms

1. Isolate the reducing valve and zero the pressure.
2. Undo the long union nut and pull away. Undo the M12 nuts and bolts.
3. Drop away the lower diaphragm chamber, the two diaphragms, diaphragm plate and the pushrod assembly.
4. Thoroughly clean the lower diaphragm chamber making sure contact faces are clean.
5. Bring the two new diaphragms together (where precoated sealant is applied this should face outwards) and slide into position.
6. Push the lower diaphragm chamber home to locate in the recess and refit the M12 nuts and bolts. Progressively and evenly tighten to a torque of 80 - 100 N m.
7. Retighten the long union nut to ensure a steam tight seal.

How to service or renew the main valve and seat

1. Isolate the reducing valve and zero the pressure.
2. Unscrew the unions and release the pipework. Remove the pilot valve housing.
3. Remove the main valve plus internal strainer screen and clean.
4. Remove the main valve spring and the main valve head. Remove the main valve seat.
5. Refit the new valve seat applying jointing compound to the seating faces and tighten to the recommended torque (e.g., DN25: 230-250 N m).
6. Where a new part has been fitted it will be necessary to reset the main valve pushrod to give the correct valve lift (e.g., DN25: 3.0 mm). Check the valve lift using a depth gauge and adjust if necessary by screwing the pushrod in or out of the diaphragm plate.