Product Description
Major Repair Kit Welch DirecTorr Part# 8811MRK for Welch 8900 - 8811MRK - OEM Equivalent
Repair Kit for Welch - OEM Equivalent
OEM-equivalent replacement, not manufactured by Welch, supplied by Vacuum Pump Supply.
Compatible Pump Models
- 8811
- 8900
What This Kit Includes
- Filters where included by kit configuration
- Vanes where included by kit configuration
- Gaskets and sealing components
- Seals and O-rings
- Bearings where included by kit configuration
When Should You Rebuild or Service the Pump?
- Reduced vacuum performance
- Slow pump-down times
- Oil leaks or worn sealing components
- Excessive exhaust smoke or oil mist
- Worn or damaged internal components
- Scheduled preventative maintenance interval reached
Complete Bill of Materials
| Part Number | Description | Qty |
|---|---|---|
| 410491 | Washer-Welch DirecTorr, Part# 410491 | 1 |
| 410643 | Shaft Seal Gasket, Fisher Scientific, Part# 410643 | 1 |
| 412969 | Spring Holder, Fisher Scientific, Welch, Maxima, DirecTorr, Part# 412969 | 3 |
| 412977 | Shaft Seal, Buna - 0. 625", Fisher Scientific, Welch, Maxima, DirecTorr, Part# 412977 | 1 |
| 412972 | Vane Spring, Fisher Scientific, Welch, Maxima, DirecTorr, Part# 412972 | 6 |
| 410929 | pump Base Legs, Welch, DirecTorr, 8806, 8811, Part# 410929 | 4 |
| 412988 | Shaft Seal, 5/8", Welch Maxima, DirecTorr, M2C, M4C, Part# 412988 | 1 |
| 413040 | Sight Glass with Chrome Base, Welch, DirecTorr, Part# 413040 | 2 |
| 413035 | Plug, O-ring, Straight Head, STL, 5/8, Welch, DirecTorr, Part# 413035 | 1 |
| 412991 | Int. Valve Spring, Conical, Welch, DirecTorr, Part# 412991 | 2 |
| 411150 | Retaining ring, Welch, Part# 411150 | 1 |
| 411285 | Washer, Welch, DirecTorr, Part# 411285 | 2 |
| 411401E-01 | Shaft Seal Kit for Welch Vacuum Pumps - 0.625" | 1 |
| 412065 | O-ring, 21.82 x 3.53 mm - Buna, Part# 412065. | 1 |
| 412642 | O-ring, 9.19 x 2.62 mm - Buna, Part# 412642. | 1 |
| 412744 | Intake Cover Gasket, Welch, DirecTorr, Part# 412744 | 1 |
| 412783 | Valve Spring, Conical, Welch, DirecTorr, Part# 412783 | 1 |
| 412945 | Oil Feed Plunger, Welch, DirecTorr, Part# 412945 | 1 |
| 412949 | Plunger Spring, Welch, DirecTorr, Part# 412949 | 1 |
| 412951 | Check Valve Spring, Welch, DirecTorr, Part# 412951 | 1 |
| 412962 | Shaft Seal, 3/8", Welch, Maxima, DirecTorr, Part# 412962 | 1 |
| 412963 | O-ring, 2.57 x 1.78 mm - Viton, Part# 412963 | 1 |
| 4400800 | Steel Ball, Welch, Duoseal, DirecTorr, Part# 4400800 | 1 |
| 4213006 | Dowel Pin, Welch, DirecTorr, Part# 4213006 | 1 |
| 413328 | Vane, Intake - GX, Welch, DirecTorr, Part# 413328 | 2 |
| 413327 | Vane, Exhaust - GX, Fisher Scientific, Welch, Maxima, DirecTorr, Part# 413327 | 2 |
| 413133 | Case Gasket, Welch, DirecTorr, Part# 413133 | 1 |
| 413058 | Drive Pin, Welch, DirecTorr, Part# 413058 | 1 |
| 413050 | Drain Pad, Welch, DirecTorr, Part# 413050 | 1 |
| 413048 | Valve, Bypass, Welch, DirecTorr, Part# 413048 | 3 |
Complete Welch Vacuum Pump Solutions
Vacuum Pump Supply stocks OEM-equivalent Welch repair kits, filters, vanes, gaskets, seals, bearings, and service parts for pump maintenance and rebuild work.
Welch Parts & Resources
Recommended Service Products
Why Buy from Vacuum Pump Supply?
- Vacuum pump specialists since 2006
- Over 15,000 vacuum pump parts and kits available
- OEM-equivalent replacement parts for hard-to-find vacuum pump models
- Fast shipping on stocked products
- Technical support from vacuum pump specialists
- Trusted by manufacturers, laboratories, universities, service companies, and maintenance teams
Frequently Asked Questions
Is this an OEM Welch product?
No. This is an OEM-equivalent product supplied by Vacuum Pump Supply.
What is the part number?
The part number is 8811MRK.
Can Vacuum Pump Supply help identify the correct part?
Yes. If you are unsure whether this is the correct product for your pump, contact Vacuum Pump Supply with your pump model and any existing part numbers.
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