• The seal chamber must be an open-frame plate liner with vortex breakers or a closed-frame plate liner designed to prevent excessive erosion.
• A mechanical seal support system must be provided as a pre-engineered turnkey system; it must include all instrumentation and fittings necessary for site installation.
• The tank must have a minimum capacity of 25 liters (6.6 U.S. gallons) and be self-filling. Inboard seal face integrity must be visually confirmable at the support system with a flow indicator.
• The distance between the seal supply and return port should be a minimum of 15 inches to maximize residency time for barrier-fluid heat dissipation.
• The system at all times must deliver barrier fluid at pressure differentials 15 psig (minimum) above the process pressure in the pump stuffing box.
• The seal system must include inline filtration of plant seal water to 1 micron. An internal standpipe on the supply leg, a three-way valve on the return leg, and a blowoff valve at the bottom of the tank must be included to allow clearing the system of any contamination after the initial installation and during its service life.
• As part of the initial supply package, documentation must include a heat generation report for each installation. The report must refer to the operating conditions for the intended shaft diameter, speed, process/barrier pressure, temperature and induced flow. The data must provide the input for a thermal equilibrium estimation and result in a calculation of the heat generated by the specific seal supplied in each case.
As regulatory legislation issues persist, a thoughtful compliance strategy will drive sealing solutions that truly optimize reliability of slurry pumps in virtually all industries.
HEINZ P. BLOCH, P.E., is a Westminster, Colo.-based process machinery consultant. TOM GROVE is executive vice president of AESSEAL, Inc., Rockford, Tenn. E-mail them at firstname.lastname@example.org and email@example.com.
1. "American National Standard for Rotodynamic (Centrifugal) Slurry Pumps for Nomenclature, Definitions, Applications and Operation," pp. 75–77, Hydraulic Institute, Parsippany, N.J. (2011), available via www.pumps.org/standards.
2. "Resource Adequacy Implications of Forthcoming EPA Air Quality Regulations," pp. 1, 6–13, U.S. Department of Energy, Washington, D.C. (Dec. 2011), posted at http://energy.gov/sites/prod/files/2011%20Air%20Quality%20Regulations%20Report_120111.pdf