A factory assembled, pressure tested, multi spring, balanced cartridge seal which utilizes Quench & Drain ports for pumped fluids that can harden or crystallize. This low profile seal fits all ANSI pumps without modification.

Features and Benefits

  • EASY TO INSTALL – No measuring is required to install the Enviro II cartridge seal.

  • NO SHAFT OR SLEEVE WEAR – There are no dynamic “O” rings on the shaft to cause fretting to your equipment and the seal is designed so that all wear parts are disposable.

  • ALIGNMENT – Stationary seats are resiliently mounted on an “O” ring and allowed to float for maximum face squareness.

  • IMPELLER ADJUSTMENT PUMPS – The Enviro II can be installed on pumps requiring an impeller adjustment after the seal is installed. Adjustments can be made without removing the seal or dismantling the pump.

  • NO MODIFICATION TO EQUIPMENT – The Enviro II low profile seal fits all ANSI pumps without modification and is superior in dimensional specifications to any other single cartridge seal commercially available.

  • API – Given pump information the Enviro II can be manufactured to meet the American Petroleum Institute specifications for many petrochemical services.

  • 3 WAY CLIPS – A clip design that not only centers seal but stops axial movement in both directions.

  • “OFF THE SHELF” AVAILABILITY – The Enviro II seal is available in 1.00″ to 3 3/4″. Larger shaft diameters are available on request.

  • PRESSURE TESTED – All Enviro II seals are pressure tested before leaving our factory.

Technical Data and Dimensions

All standard dimensions will be customized to fit your application.

1 1/81.7501.9371.6872.7964.01.0151.682.562
1 1/42.0002.1871.9373.0624.01.0151.682.562
1 3/82.0002.1871.9373.0624.01.0151.682.562
1 1/22.2502.4372.1873.3435.01.0151.803.562
1 5/82.3752.5622.3123.4725.01.0151.803.562
1 3/42.5002.6872.4373.6255.51.0151.803.562
1 7/82.6252.8122.5623.7805.51.0151.803.562
2 1/82.8753.1252.8124.3126.01.0151.875.687
2 1/43.0003.2502.9374.4376.01.0151.875.687
2 3/83.1253.3753.0624.4376.01.0151.875.687
2 1/23.2503.5003.1874.6256.01.0151.875.687
2 5/83.4683.6253.4064.6716.51.1391.750.687
2 3/43.7504.0003.6875.0626.51.1391.750.687
2 7/83.7504.0003.6875.0626.51.1391.750.687
3 1/84.0004.2503.9375.5628.01.1391.750.687
3 1/44.2504.5004.1875.9378.01.1391.750.687
3 3/84.2504.5004.1875.9378.01.1391.750.687
3 1/24.5004.7504.4376.1878.01.1391.750.687
3 5/84.5004.7504.4376.1878.01.1391.750.687
3 3/44.7505.0004.6876.4378.01.1391.750.687

SIZES: Metric and sixteenth seals available against specific orders. Larger shaft diameters available against speficic orders.


1316 SS*11316 SS
3316 SS*13316 SS*
4Viton**14316 SS*
5Hastelloy C15Carbon*
6316 SS16Vitron**
7Viton**17316 SS
8Chemical Grade Carbon*18316 SS
9Ceramic – AI2O3 99.7% 19316 SS*

*Consult factory

Special material and design features available upon request.

Aflas is a registered trademark of Asahi Flass Co. Ltd.
Hastelloy is a registered trademark of Cabot Corp.
Viton and Kalrez are registered trademarks of Dupont.

Recommended Seal Environmental Controls

Water Quench

With a ‘Lip-Seal’ installed, there is no leakage to the atmospheric side of the seal. Quench water pressure should not exceed 5 psi.

Steam Quench

With the carbon throttle bushing installed the tight clearance over the sleeve minimizes leakage to atmosphere.

Easy to install, no measuring

  1. Clean stuffing box face, clean and deburr pump shaft or sleeve.
  2. Lubricate seal sleeve ‘O’ ring with neutral or silicone grease.
  3. Position seal on the shaft to within 1/4″ of the bearing housing.
  4. Reassemble remaining pump parts.
  5. Slide the mechanical seal into position. Tighten all gland bolts, ensuring the gland ‘O’ ring mates with the stuffing box face.
  6. Tighten all set screws to the shaft or the sleeve.
  7. Remove all centering & loading clips.
  8. Connect and pressurize flush.

Total Warranty

All Robco seals are manufactured to exact standards, and are guaranteed free of defects in materials and workmanship. All seals are guaranteed for 90 days from delivery, excepting negligence, misuse and abuse, and will deliver at our expense a new seal to replace any seal found to be defective within said period. No registration card is required.

The warranty is expressly in lieu al all warranties, expressed or implied, and of all obligation or liabilities on our part, including any liability for incidental or consequential damages.


The temperature limits, pH ranges, pressure ratings, feet per box and shaft speeds shown throughout this pamphlet are representative; the service life and performance of these products can be affected by elevated temperatures and other operating conditions such as chemical resistance, shaft speeds, pressure and equipment in which that the product is being installed. The ratings supplied are suggested as a guideline and should only be used for evaluating your specific application. When in doubt, contact Robco or your ENVIROPAK distributor. The information contained in the pamphlet should not be considered to be a warranty, expressed or implied, including, but not limited to, a warranty of merchantability or fitness for a particular purpose. In no event shall Robco be liable for any incidental or consequential damages resulting from the use, misuse or inability to use the products. This exclusion applies regardless of whether such damages are sought based on breach of warranty, breach of contract, negligence, strict liability in tort, or any other legal theory.

All Robco mechanical seals are manufactured, assembled and tested in America.