Hydraulic Filter Elements — Quick Reference (English)

Items: PH-312-03· PH312-11-CG

1) What These Are (Plain English)

Both belong to the same PH312 family — a pressure-line filter housing mounted on the pipe between pump and valves. The head is a heavy cast-steel unit with threaded ports, rated for high pressure (often up to 315–420 bar class depending on head casting).

• PH-312-03 = shorter/lower-flow variant in the PH312 family

  
  

• PH312-11-CG = longer/higher-dirt-holding variant in the same PH312 family

  
  

• CG at the end = C = NBR seal (black/dark grey, mineral oil) + G = a structural/end-cap variant (often relates to centre tube, bypass disc, or bowl latch style — treat it as “part of the identity, don't drop it when reordering”)

  
  

⚠️ 03 and 11 are different lengths. Even though they share the PH312 head family, the centre locator / seal lands differ — never swap 03 ↔ 11 just because “the box looks close.”

2) What to Check Before Installation

A) Housing nameplate (near the inlet/outlet ports)

• Model should read PH312… plus pressure rating (bar / MPa) and port size (e.g. SAE flange or metric thread)

  
  

• FLOW ARROW stamped on the head — must match pipe direction

  
  

• Any “MAX WP” / temperature note

  
  

B) Old element (ruler check)

• Overall height — 03 is noticeably shorter than 11

  
  

• OD / centre-hole ID — should match the new one exactly

  
  

• O-ring colour: should be black/dark grey (NBR) for “CG”. If the old one is brown/red (Viton), stop and confirm the fluid/temperature spec before using a different seal compound.

  
  

3) Replacement — Pressure-Side (Extra Caution)

Because these sit on the pump-discharge leg, trapped pressure is hazardous:

1. Close upstream isolation if fitted → bleed slowly through the head vent until the gauge reads 0 bar and no more hissing.

   
   

2. Support the bowl — pressure hardware is heavy; don’t let it hang on piping.

   
   

3. Release the retainer / clamp → lift element straight out (direction depends on head — some PH312 pull up, some pull down; follow the arrow and the head casting).

   
   

4. Check bowl bottom for bright metal shavings (pressure-side debris = pump/valve wear, act on it).

   
   

5. Wipe sealing faces → thin film of clean hydraulic oil on the O-ring (no grease, no sealant).

   
   

6. Seat element square on the centre support (feel it locate — off-centre = bypass or collapse risk under pressure).

   
   

7. Reassemble → torque evenly per head spec → close vent.

   
   

8. Bring pressure back slowly → stand by for leaks for the first few minutes — pressure-side leaks escalate fast.

   
   

4) Procurement — What to Write

5) One-Line BOM (copy-paste)

• PH-312-03— Pressure-line element, PH312 family (short), NBR(+variant), fits PH312 head nameplate only — full depressurize before opening

  
  

• PH312-11-CG— Pressure-line element, PH312 family (longer, CG variant), NBR(+variant), fits PH312 head nameplate only — not interchangeable with 03 by length

  
  

Field rule (keep it safe)

Pressure-side housings: vent slow, support the bowl, seat square, bring pressure up slow.

And: if you see two PH312 boxes on the same shelf, the 03 and 11 must be labelled clearly — a ruler on the old element (just H in mm) written on the BOM line prevents the "they look the same" mistake forever.