ASTM D93 – Pensky-Martens Closed Cup Method

ASTM D93 is a closed-cup flash point test method widely used for petroleum products with flash points between 40°C and 370°C.

Test Principle

Sample placed in sealed test cup
Heated at defined rate (1–2°C per minute)
Ignition source applied at temperature intervals
Flash observed through sight port

Procedure Steps

Fill test cup to specified mark
Seal lid properly
Start controlled heating
Apply ignition at defined intervals
Record temperature at flash

Critical Control Parameters

Heating Rate

Must follow ASTM specification
Deviation alters result significantly
Verify using calibration reference

Ignition Interval

Applied at defined temperature steps
Too frequent → premature flash
Too late → delayed flash

Common ASTM D93 Errors

Improper lid sealing
Incorrect ramp rate
Temperature sensor drift
Contaminated test cup
Non-certified CRM

Compliance & Reporting

Report to nearest 1°C
Record barometric pressure if required
Use certified reference materials
Maintain traceability documentation

ASTM compliance requires strict adherence to heating rate and ignition interval.