Seal duty
Awaiting Valid Duty Parameters
Adjust the parameters on the left to compute live hydraulic values, ranges, and sizing verdicts.
Seals failing again?
Repeat seal failures are a symptom, not the problem. We diagnose the cause — materials, flush, installation or alignment — and fit the right seal.
Mechanical seal selection explained
Faces and secondaries
Seal faces are the wear couple: SiC/SiC for most chemical duties, SiC/carbon where running against a softer face helps start-up, and tungsten carbide for abrasive services. The secondary sealing — the part that actually touches the chemical — matters more: FKM degrades in HCl, EPDM handles caustic and hypochlorite, and PTFE bellows survive almost everything at temperature.
The selector checks the elastomer ratings from the compatibility matrix at your temperature and steers to PTFE bellows where FKM or EPDM fail.
API 682 flush plans
Flush plans keep the seal chamber clean, cool and pressurized. Plan 11 recirculates pump discharge to the seal — the default for clean chemical duties. Plan 31 settles solids with a cyclone, Plan 32 injects clean external flush for solids or dilution, and Plan 62 quenches the atmosphere side for crystallizing services. Hot water duties move to Plan 23.
The selector recommends the plan from your solids and temperature, and flags the gland-water guidance range for Plan 32 as typical figures to confirm per API 682.
Beyond the materials
Most repeat failures are not material problems: shaft misalignment, dry running, cavitation and incorrect installation kill seals faster than any chemical. Fix the system, then the seal. Teflow’s seal repair service re-machines faces, fits correct elastomers and checks the pump before the seal — call +91 98251 62709 for a failure analysis.
Technical & Operational FAQs
Q1.What seal material for HCl?
SiC/SiC faces with PTFE bellows (or EPDM O-rings at moderate temperature) — FKM degrades in HCl. Flush with Plan 11 recirculation. PTFE bellows seals are the standard choice on PFA-lined HCl pumps.
Q2.What is an API 682 flush plan?
A standardized piping arrangement that controls the seal chamber environment. Plan 11 recirculates discharge to the seal; Plan 31 settles solids via cyclone; Plan 32 injects external clean flush; Plan 62 quenches the atmosphere side. Selection depends on liquid, solids and temperature.
Q3.Why does my seal fail every few months?
Look past the materials: misalignment, dry running, cavitation, and installation damage cause most repeat failures. Check the pump first — bearings, alignment and NPSH — then review the seal spec. The troubleshooting guide walks through the common causes.
Q4.When do I need a double seal?
For hazardous, toxic or emission-critical liquids where any leakage is unacceptable, and for vacuum suction or gas-bearing services. Double seals use a barrier fluid between two faces; they are more complex and need a support system.
Q5.What is gland water for Plan 32?
Clean external flush injected into the seal chamber, typically 2–5 L/min at 2–3 bar above seal chamber pressure (typical guidance — confirm per API 682). It dilutes or carries away solids and keeps the faces cool.
Related Engineering Tools
NPSH Available Calculator
Chemical Pump Sizing
Unit Converter Suite
Seal Failure Guide
Mechanical Seals Guide
Seal Repair Service
Need a custom hydraulic audit or specific duty curve verification? Call +91 98251 62709 or Request a Detailed Engineering Quote.