Alfa Laval Unique PMO Plus® Mixproof Valve

The Alfa Laval Unique PMO Plus® mixproof valve offers all the performance of a Unique Mixproof valve and, in addition, meets the requirements of 3-A/PMO standards. The mixproof valve design allows clean-in-place (CIP) fluid to flow to clean one chamber while product is running in the other chamber, without the risk of cross-contamination. Eliminating clean-in-place (CIP) downtime and allowing automated product transfer are just two of the advantages that mixproofs provide. Unique PMO Plus Mixproof Valves combine Alfa's superior cleanability and reliability with the required features for meeting the PMO standard making it a powerful solution for dairy applications.

Unique PMO Plus valves are authorized to carry the 3-A symbol.

The Pasteurized Milk Ordinance (PMO)

Paragraph 15p(B) of the Pasteurized Milk Ordinance (PMO) outlines the requirements for the use of mixproof valves in applications involving milk products and cleaning solutions to ensure the hygienic and safe separation of dairy products flowing concurrently through the same valve.

The PMO requires that:

  • Both valve seats must be position detectable
  • The leakage chamber, found in all mixproof valves, must have the same cross-sectional area as the valve body port connections
  • The actuator must be fail-safe by spring-to-close

In 2007, the Food and Drug Administration (FDA) changed the PMO to allow clean-in-place (CIP) solution to clean one valve seat while product is flowing in the opposite housing. This change virtually eliminates CIP downtime, so processors can run continuous dairy operations and increase production.

In 2008 the FDA issued memorandum M-b-356, confirming that Alfa Laval’s Unique PMO Plus mixproof valve is Pasteurized Milk Ordinance paragraph 15p(B) compliant.

The following benefits make the Unique PMO Plus stand out from the competition:

  • Proven design: Same fundamental technology used in the industry for more than a decade
  • Retrofittable: Replacement of a few components enables conversion of installed Unique PMO valves to Unique PMO Plus
  • Only three elastomers in the isolation chamber: Minimizes risk of product contamination
  • Tested and FDA compliant to 145 psi: The highest operating pressure available for the widest range of process applications
  • Designed with a mix of radial and axial seals: A proven, leading design to protect product
  • Standard, single unit actuator: Simple operation with fewer moving parts
  • Same wetted and actuator service kits as the unique PMO valve: No need to learn or stock new parts
  • Maintenance friendly: No adjustments are required when reassembling the valve after service

This Unique PMO Plus Mixproof valve is based on the well proven and exceptionally flexible design of the Unique PMO Mixproof valves from Alfa Laval. It meets the demands from the 3-A/PMO (Pasteurized Milk Ordinance paragraph 15p(B)) standards saying that all movements have to be detectable, as well as the vent tube has to have the same or greater area than the connection pipe. Furthermore, the Unique PMO Plus meets the FDA demands for seat lift compliance M-b 356. This allows CIP flow to clean one chamber while product is running in the other chamber, thus eliminating CIP downtime. Finally, the actuator is fail-safe by spring-to-close.

Working Principle

Unique PMO Plus is remote-controlled by means of compressed air. The valve is a normally closed (NC) valve. The valve has two independent plug seals, forming a leakage chamber between them which is at atmospheric pressure or less during every working condition. In the rare case of fluid passing a valve seat, the fluid will enter the leakage chamber and be discharged through the leakage outlet. When the valve is open, the leakage chamber is closed.


This PMO Plus edition of the Unique Mixproof valve is a high-end valve with regards to process security as well as from a sanitary point of view. The valve plugs are always balanced in both upper and lower valve body, securing no sensitivity to pressure spikes. The lower and upper seats are position-detectable by the ThinkTop® and a yoke-mounted, external sensor.

Unique PMO vs. Unique PMO Plus
Product Wetted Steel Parts316L
Other Steel Parts304
Product Wetted SealsNBR (std.), EPDM, HNBR, or FPM
Other SealsCIP seals: EPDM
Actuator seals: NBR
FinishExternal bright/internal polished Ra<32µ"

Note: The Ra values are only for the internal surface.

Technical Data
Product Pressure (max)145 psi (for higher pressure, contact CSI)
Product Pressure (min)Full vacuum
Temperature Range23°F - +257°F (Depending on seal material) (For higher temperature, contact CSI)
Air Pressure116 psi
Dimensional Data
Size (in)22.534
Weight (lb)33.00053.00053.00075.000

**The measure C can always be calculated by the formula C = ½ID-upper + ½ID-lower + 1 inch.

Pressure Drop/Capacity Diagrams


Note: For the diagrams the following applies: Medium: Water (68°F). Measurement: In accordance with VDI 2173.

Valve Body Combinations

Spare Parts

PMO Plus Service Kits

Unique PMO Plus Mixproof Valve Parts List

PMO Plus Mixproof Spare Parts
Part22.534Diagram Key
Complete Actuator9613055468961309950996130995099613083769-
Upper Stem96130101029613007401961300740196130074021
Air Fitting, Yellow96119941719611994171961199417196119941713
Air Fitting, Blue96119937809611993780961199378096119937803
Air Fitting, Red96119941729611994172961199417296119941723
Stop for Upper PistonN/A9613005301961300530196130053024
O-Ring, NBR96119934999611993499961199349996119934995
Guide Ring, Turcite96130084089613008408961300840896130084086
O-Ring, NBRN/A9611993514961199351496119935147
Upper PistonN/A9613005601961300560196130056028
O-Ring, NBRN/A9611993512961199351296119935139
Spring Assembly961301250196130075019613007501961302560310
Distance Spacer9613010202N/AN/AN/A11
Spring Assembly961301310296130095029613009502961200950214
Main Piston961301320196130057019613005701961301590117
Guide Ring, Turcite961300840996130084109613008410961300841118
O-Ring, NBR961199350596119935079611993507961199350919
O-Ring, NBR961199350396119936079611993607961199360720
Guide Ring, Turcite961300840396130084049613008404961300840422
O-Ring, NBR9611992228961199148996119914892234067523
Retaining Ring961302480296130248039613024803961302480424
Cover Disk961300580296130058039613005803961300580425
O-Ring, NBR961199352896119934959611993495961199353026
Inner Stem961301060396130073039613007303961300730227
Piston Rod961301340296130060029613006002961300600229
Lower Piston961301380196130055019613005501961301660130
O-Ring, NBR4215342153421534215331
Guide Ring, Turcite961300840596130084069613008406961300840732
O-Ring, NBR2234127596119935089611993508961199351033
Spindle Liner961303350196130090019613009001961300900142
Guide Ring, PTFE961300841496130084159613008415961300842145
Upper Sealing Element961300640496130188049613018804961307130148
Guide Ring, PTFE961300840296130084029613008402961300840254
Upper Plug961345860196134587019613458703961345880155
Clamp w/o Nut961302160196130217019613021701961302180164
Lower Plug961307050196130706019613070701961307080175
Lower Sealing Element961302410496130243049613024304961307150179
Guide Ring, PTFE961300841496130084159613008415961300842180
Bolt for Indication961309260296130926019613092601961309260182
Sensor for Indication961199454196119945419611994541961199454183
Plate for Sensor for Indication961309570196130957019613095701961309570184
Intermediate Piece961301912196130192159613019213961301931737
O-Ring, EPDM961199355596119935729611993572961199357238
O-Ring, NBR961199363796119936419611993641961199364547
O-Ring, EPDM961199363696119936409611993640961199364447
O-Ring, HNBR961199363996119936439611993643961199364747
O-Ring, FPM961199363896119936429611993642961199364647
Lip Seal, NBR961300854696130085479613008547961300853749
Lip Seal, EPDM961300852696130085319613008531961300853649
Lip Seal, HNBR961300852996130085349613008534961300853949
Lip Seal, FPM961300852896130085339613008533961300853849
Seal Ring, NBR961309511596130951169613095116961309512456
Seal Ring, EPDM961309530996130953129613095312961309531956
Seal Ring, HNBR961309530896130953119613095311961309531856
Seal Ring, FPM961309510896130951119613095111961309512256
Lip Seal, NBR961300871896130087189613008718961300871857
Lip Seal, EPDM961300871196130087119613008711961300871157
Lip Seal, HNBR961300871496130087149613008714961300871457
Lip Seal, FPM961300871396130087139613008713961300871357
Seal Ring, NBR961309521596130952169613095216961309522474
Seal Ring, EPDM961300890996130089129613008912961300891874
Seal Ring, HNBR961300890896130089119613008911961309521774
Seal RIng, FPM961309520896130952119613095211961309522274
O-Ring, NBR961199363796119936419611993641961199364576
O-Ring, EPDM961199363696119936409611993640961199364476
O-Ring, HNBR961199363996119936439611993643961199364776
O-Ring, FPM961199363896119936429611993642961199364676
Lip Seal, NBR961300854696130085479613008547961300853777
Lip Seal, EPDM961300852696130085319613008531961300853677
Lip Seal, HNBR961300852996130085349613008534961300853977
Lip Seal, FPM961300852896130085339613008533961300853877
Valve Body 11-00961307090196130710019613071101961307120150
Valve Body 12-00961307090596130710059613071105961307120550
Valve Body 21-00961307090796130710079613071107961307120750
Valve Body 22-00961307090996130710099613071109961307120950
Valve Body 11-90961307090296130710029613071102961307120250
Valve Body 12-90961307090696130710069613071106961307120650
Valve Body 21-90961307090896130710089613071108961307120850
Valve Body 22-90961307091096130710109613071110961307121050
Valve Body 11-180961307090396130710039613071103961307120350
Valve Body 11-270961307090496130710049613071104961307120450

Unique PMO Plus Mixproof Valve Parts List

Rebuilding Set PMO Plus to PMO Plus CP
Lower Plug, cpl., NBR9613466217961346621896134662199613466220
Lower Plug, cpl., EPDM9613466221961346622296134662239613466224
Lower Plug, cpl., HNBR9613466225961346622696134662279613466228
Lower Plug, cpl., FPM9613466229961346623096134662319613466232

Unique PMO Plus Mixproof Valve Parts List

PMO Plus Radial Installation
Part22.5 & 34Diagram Key
Guide Ring9613008422961300842296130084266
O-Ring, NBR9611993349961199334996119941137
O-Ring, NBR9611993705961199370596119937058

Unique PMO Plus Mixproof Valve Parts List

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