AST BLOG: Use of Outside Component Seal for Corrosive Process Fluids
Mechanical seals can be expensive with long lead times when requesting exotic metals like Alloy 20 or Hastelloy B/C to combat process fluids such as chlorine, chlorides, sulfuric acid, bromine and others. A multi-spring outside component seal is often a viable option in order to get the high-quality construction of a cartridge style seal, minus the cost of exotic metals.
Advanced Sealing Technology offers our AST50 multi-spring component seal for challenges with stainless steel and corrosive process fluids. The AST50 is designed for four primary uses:
1. Where an outside seal is required.
2. As a low-cost replacement for seals made of exotic metals.
3. In corrosive fluids that attack inside-mounted mechanical seals.
4. In food processing where the seal must be cleaned in place for sanitation.
The AST50 has no metal parts in direct contact with the pumped fluid. The multiple springs are also isolated form the fluid. Unlike reverse-mounted inside seals, the AST50 is hydraulically balanced for use as an outside seal.
The AST50 mechanical seal is readily accessible, not hidden in the stuffing box, so it’s easy to install and replace. Since the proper spring compression is preset, installation is simple. The following steps are specifically for a Goulds 3196, but assembly is similar for many other pumps including Fybroc, Goulds FRP pumps, etc.
Step 1: Just slide the AST50 rotary unit over the shaft until it comes into contact with the bearing housing, with the seal ring facing the impeller.
Step 2: Position the L-shape stationary in the gland, then the gland is bolted to the pump box cover.
Step 3: Position the box cover (with clamped stationary/gland) onto the pump, then box cover is bolted onto the pump.
Step 4:
· Reassemble the pump and reset the impeller clearance.
· Slide the gland over the gland studs. Make sure the stationary is centered over the shaft and tighten the gland nuts evenly in a diagonal sequence. To prevent stationary face distortion, do not over tighten (50-60 inch-lbs.).
· Slide the AST50 rotary unit towards the stationary until the faces are in contact. Tighten the set screws evenly and securely to lock the rotary unit in position (50-60 inch-lbs.).
· Remove the retaining clips (circled red in the photo). The rotary unit is set at the correct operating length.
Step 5: Rotate the shaft by hand to check for obstructions or contact (Note: Do not start the equipment dry).
Technical data as well as additional information on our AST50 outside component seal can be found in our brochure at the following location: https://www.astseals.com/external-seal-ast50.
For further assistance, please call or email AST for help:
401-783-8001