High Pressure Plunger Pump · Frame size 36 PFR
3621X
This triplex (three plunger rods) positive displacement, reciprocating plunger pump is part of the Cat Pumps X-Series , engineered for maximum life in demanding applications such as seawater reverse osmosis (SWRO). The model 3621X features a 316 stainless steel inlet manifold, duplex stainless steel discharge manifold, 316 stainless steel valve assemblies, solid ceramic plungers, and standard NBR (Buna-N) low-pressure seals and O-rings.
Technical specifications
| Flow rate | 94.6 l/min |
|---|---|
| Operating pressure | 138 bar |
| Speed | 870 min⁻¹ |
| Inlet port | 1 1/2" NPT(F) |
| Discharge port | 1" NPT(F) |
| Shaft diameter | 35 mm |
| Material | Stainless Steel |
Downloads
CAD files
Spare parts
Click an item in the drawing or in the parts list to add it to your request list. We turn it into a quotation – no order is placed.
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3 kits bundle wearing parts of this pump ↓
Exploded view

Parts list
| Item | Part no. | Description | Qty | Add to request list |
|---|---|---|---|---|
| 5 | 96049 | Screw, HHC Sems (M10x25)S | 8 | |
| 8 | 134604 | Cover, Bearing [06/18]ALE | 2 | |
| 9 | 815279 | Shim, Split, 2-Piece 0 - 2FBR | 2 | |
| 10 | 12398 | O-Ring, Bearing Cover - 70DNBR | 2 | |
| 11 | 13296 | Seal, Oil, Crankshaft 0 - 2NBR | 2 | |
| 12 | 855049 | Shim, Split, 2-Piece 0 - 2S | ||
| 15 | 29326 | Bearing, RollerSTL | 2 | |
| 20 | 126725 | Rod, Connecting Assembly (Includes: 21, 22, 23) (Model 3521DHS)BZ | 3 | |
| 21 | 126749 | Washer, Locking (M10)STCP | 3 | |
| 22 | 126593 | Washer, Flat (M10.5)STCP | 6 | |
| 23 | 122045 | Screw, HH (M10x55)STZP | 6 | |
| 25 | 29325 | Crankshaft, Dual End (M48)FCM | 1 | |
| 31 | 828710 | Protector, Oil Cap with Foam Gasket 1PE | 1 | |
| 32 | 43211 | Cap, Oil FillerABS | 1 | |
| 33 | 14177 | O-Ring, Oil Filler Cap - 70DNBR | 1 | |
| 34 | 126743 | Bolt, Eye (M12x1.75) (For Lifting Pump Only)STCP | 1 | |
| 37 | 92241 | Gauge, Oil, Bubble with Gasket - 80D 1 - 2PC | 1 | |
| 38 | 44428 | Gasket, Flat, Oil Gauge - 80DNBR | 1 | |
| 40 | 125753 | Screw, HHC, Sems (M8 x 25) (Model 2530E)S | 8 | |
| 48 | 25625 | Plug, Drain (1/4" x 19 BSP[M])STCP | 1 | |
| 49 | 23170 | O-Ring, Drain Plug - 70DNBR | 1 | |
| 50 | 45936 | Cover, Rear (See Tech Bulltin 118)ALE | 1 | |
| 51 | 16612 | O-Ring, Cover - 70DNBR | 1 | |
| 53 | 134784 | Crankcase Assembly (Includes 54)ALE | 1 | |
| 54 | 27488 | Pin, GuideS | 2 | |
| 56 | 27790 | Pan, OilPOP | 1 | |
| 59 | 92538 | Screw, HHC, Sems (M6 x 16) (Model 2530E)S | 2 | |
| 64 | 43864 | Pin, CrossheadCM | 3 | |
| 65 | 49166 | Rod, Plunger (Model 3521DHS)SSHB | 3 | |
| 69 | 126587 | Washer, Oil SealSTCP | 3 | |
| 70 | 100488 | Seal, Oil, CrankcaseNBRS | 3 | |
| 75 | 43865 | Slinger, BarrierS | 3 | |
| 88 | 45676 | Washer, Keyhole (M16)S | 3 | |
| 90 | 43957 | Plunger (M32x145)CC | 3 | |
| 95 | 89778 | Stud, Plunger Retainer (M10x135)SS | 3 | |
| 96 | 20189 | Back-up-Ring, Plunger RetainerPTFE | 3 | |
| 97 | 11345 | O-Ring, Plunger Retainer - 70DNBR | 3 | |
| 98 | 44085 | Gasket, Plunger Retainer (M7) Model 3501, 3501C, Gasket, Plunger Retainer (M10) Model 3511, 3511CSS | 3 | |
| 99 | 44084 | Retainer, Plunger (M10)SS | 3 | |
| 100 | 44119 | Retainer, Seal, RearPPG | 3 | |
| 100 | 814279 | Retainer, Seal, 2-PiecePPG | 3 | |
| 101 | 44106 | Wick, Long Tab | 3 | |
| 104 | 43875 | O-Ring, Inlet Adapter - 70DNBR | 3 | |
| 105 | 45562 | Adapter, Inlet, Low-PressureSS | 3 | |
| 106 | 44098 | Seal, Low-Pressure, with SS - SpringNBR | 3 | |
| 106 | 76298 | Seal, Low-Pressure, with SS-Spring | 3 | |
| 107 | 44101 | Washer, Low-Pressure SealSS | 3 | |
| 110 | 77365 | Manifold, InletSS | 1 | |
| 112 | 11379 | O-Ring, Inlet Manifold - 70DNBR | 3 | |
| 117 | 44585 | Screw, HSH (M14x40)S | 4 | |
| 122 | 665435 | SpacerSS | 3 | |
| 123 | 12391 | O-Ring, V-Packing Cylinder - 70DNBR | 3 | |
| 124 | 670197 | Cylinder, PackingSS | 3 | |
| 126 | 665431 | Backup Ring, PackingPVDF | 3 | |
| 127 | 670333 | Packing, SquarePFB | 3 | |
| 128 | 670196 | Washer, SpringSS | 3 | |
| 129 | 670195 | Sleeve, PlungerD | 3 | |
| 141 | 49743 | Spring, Coil, LargeSS | 3 | |
| 155 | 48860 | O-Ring, V-Packing Cylinder - 90DNBR | 3 | |
| 156 | 48362 | Backup Ring, V-Packing, Spacer, OuterD | 6 | |
| 162 | 48363 | Backup-Ring, Valve SeatD | 6 | |
| 163 | 26142 | O-Ring, Seat - 80DNBR | 6 | |
| 164 | 44612 | Seat, SteppedSS | 6 | |
| 166 | 44108 | ValveSS | 6 | |
| 167 | 44109 | Spring, ValveSS | 6 | |
| 168 | 44728 | Retainer, SpringPVDF | 6 | |
| 170 | 44729 | Washer, Spring RetainerSS | 6 | |
| 170 | 44729 | Washer, Spring RetainerPVDF | 6 | |
| 171 | 44644 | Coil Spring (70kg), Valve PlugSS | 6 | |
| 172 | 89827 | O-Ring, Valve Plug - 90DNBR | 6 | |
| 173 | 48364 | Backup-Ring, Valve PlugD | 12 | |
| 174 | 670143 | Plug, ValveSS | 6 | |
| 176 | 129759 | Plate, ValveSSD | 2 | |
| 177 | 32393 | Screw, HSH (M14 x 70)STZF | 8 | |
| 185 | 129754 | Manifold, DischargeSSD | 1 | |
| 188 | 89981 | Screw, HSH (M12 x 70)S | 8 | |
| 250 | 855042 | Protector, Shaft with Two (2) Screws, Lockwashers and WashersPOP | 1 | |
| – | 6124 | Gasket, Liquid (3 oz. / 0,1 l) | 1 | |
| – | 6139 | Lubricant, Anti-Seize (8 oz) (Model 1531) | 1 | |
| – | 30696 | Reverse Pliers (Not Shown) | 1 | |
| – | 32273 | Crankcase Oil Seal Removal and Installation Kit (Not Shown) | 1 | |
| – | 34021 | Key (M10 x 8 x 70) 1 | 1 | |
| – | 34039 | Mount, Direct (S) 1 | 1 | |
| – | 34314 | Kit, Oil Drain (3/8" x 48") (Not Shown) | 1 | |
| – | 76514 | Mount, Rail Assembly (S) (Includes: 34039) 1 | 1 | |
| – | 80540 | Screw, Adjusting (M12 x 100) 2 | 2 | |
| – | 910620 | Head Complete with NBR & PFB Seals, NBR O-Rings (Model 3621X) | 1 | |
| – | 910621 | Head Complete with ST2 & PFB Seals, NBR O-Rings (Model 3621XD) | 1 | |
| – | 990013 | Hub, "B", 35 mm (STL) 1 | 1 | |
| – | 6133 | Oil, Crankcase, Can 4l | 1 |
in the request listcovered by a requested kit
Seal and valve kits
A kit bundles the wearing parts of one assembly. Selecting it highlights the items it covers in the drawing and the parts list – once requested, they stay marked.
Seal kits
Seal kit
32522
NBR (STD)Medium Nitrile (Buna-N)
contains 10 items · one kit per pump
Parts list
- 9711345O-Ring, Plunger Retainer - 70D3×
- 10443875O-Ring, Inlet Adapter - 70D3×
- 10644098Seal, Low-Pressure, with SS - Spring3×
- 11211379O-Ring, Inlet Manifold - 70D3×
- 12312391O-Ring, V-Packing Cylinder - 70D3×
- 126665431Backup Ring, Packing3×
- 127670333Packing, Square3×
- 129670195Sleeve, Plunger3×
- 15548860O-Ring, V-Packing Cylinder - 90D3×
- 15648362Backup Ring, V-Packing, Spacer, Outer6×
Seal kit
77077
NBR (STD)Medium Nitrile (Buna-N)
contains 10 items · one kit per pump
Parts list
- 9711345O-Ring, Plunger Retainer - 70D3×
- 10443875O-Ring, Inlet Adapter - 70D3×
- 10676298Seal, Low-Pressure, with SS-Spring3×
- 11211379O-Ring, Inlet Manifold - 70D3×
- 12312391O-Ring, V-Packing Cylinder - 70D3×
- 126665431Backup Ring, Packing3×
- 127670333Packing, Square3×
- 129670195Sleeve, Plunger3×
- 15548362Backup Ring, V-Packing, Spacer, Outer3×
- 15648860O-Ring, V-Packing Cylinder - 90D6×
Valve kits
Valve kit
77078
NBR (STD)Medium Nitrile (Buna-N)
contains 9 items · 2 kits per pump
Parts list
- 16248363Backup-Ring, Valve Seat3×
- 16326142O-Ring, Seat - 80D3×
- 16444612Seat, Stepped3×
- 16644108Valve3×
- 16744109Spring, Valve3×
- 16844728Retainer, Spring3×
- 17044729Washer, Spring Retainer3×
- 17289827O-Ring, Valve Plug - 90D3×
- 17348364Backup-Ring, Valve Plug6×
More models in frame size 36 PFR
3621XD
- Flow rate
- 94.6 l/min
- Operating pressure
- 138 bar
- Speed
- 870 min⁻¹
- Material
- Stainless Steel
3622X
- Flow rate
- 94.6 l/min
- Operating pressure
- 138 bar
- Speed
- 870 min⁻¹
- Material
- Duplex Stainless Steel
3631X
- Flow rate
- 136 l/min
- Operating pressure
- 83 bar
- Speed
- 800 min⁻¹
- Material
- Stainless Steel
3631XD
- Flow rate
- 136 l/min
- Operating pressure
- 83 bar
- Speed
- 800 min⁻¹
- Material
- Stainless Steel