CMC Toxic Gas Detection & Monitoring Flashcards
6 cards from real CMC practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 6 CMC Toxic Gas Detection & Monitoring flashcards as text
What is the TWA (Time-Weighted Average) PEL for carbon monoxide established by OSHA?
Answer: 50 ppm
OSHA's 8-hour TWA PEL for carbon monoxide is 50 ppm; exposure above this level requires respiratory protection.
Which marine cargo residue is most likely to produce benzene vapor requiring PID monitoring?
Answer: Crude oil and petroleum distillates
Crude oil and petroleum distillate residues are primary sources of benzene vapor, a known carcinogen requiring PID or specific benzene tube monitoring.
When calibrating a multi-gas detector for marine use, what gas mixture is typically used for LEL calibration?
Answer: 50% LEL methane in air
Standard practice uses a certified calibration gas of 50% LEL methane in air (approximately 2.5% methane) to set the LEL sensor response.
A Marine Chemist finds H2S readings of 3 ppm in a cargo tank. What should the certificate state?
Answer: Safe for workers with H2S monitoring in place
Low-level H2S (below 1 ppm ACGIH TLV) may permit entry with monitoring requirements noted on the Marine Chemist certificate.
What type of detector is required when evaluating a tank that previously held leaded gasoline?
Answer: PID with an appropriate lamp plus lead-specific monitoring
Leaded gasoline residue presents both LEL and benzene/VOC hazards, requiring a PID in addition to standard combustible gas testing for complete hazard assessment.
Why must catalytic bead sensors NOT be used in oxygen-deficient atmospheres?
Answer: Combustion on the bead requires sufficient oxygen to function accurately
Catalytic bead sensors require ambient oxygen to oxidize the gas on the bead; oxygen deficiency suppresses the reaction, causing falsely low or zero LEL readings.