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ASE Transit Bus

H1 Transit Bus — CNG Engines — practice test

Studying for H1 (Transit Bus — CNG Engines)? Overhaul Prep has 173 verified H1 questions written to the current task list — in the same formats the real exam uses (direct, Technician A/B, EXCEPT and most-likely-cause). Every answer comes with a written explanation, so you learn why instead of memorising a letter.

173H1 questions
100%with explanations
9,711questions in total
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Sample H1 questions

Straight from the bank — answers highlighted, with the explanation underneath.

On a transit bus CNG fuel system, the cylinders store fuel at a full service (settled) pressure of about:

  1. 250 psi
  2. 900 psi
  3. 3,600 psi
  4. 10,000 psi
WhyThe industry-standard CNG service pressure is 3,600 psi (about 24.8 MPa) measured as a settled pressure at 70 F; older systems used 3,000 psi.

Two technicians discuss a CNG leak in an enclosed maintenance bay. Technician A says leaking CNG rises and accumulates at the highest point of the space. Technician B says because CNG is heavier than air it pools on the floor. Who is correct?

  1. Technician A only
  2. Technician B only
  3. Both Technicians A and B
  4. Neither Technician
WhyMethane's vapor density is about 0.55, so it is lighter than air and rises; Technician B is describing LPG/propane behavior, which is heavier than air.

All of the following statements about methane/CNG are true EXCEPT:

  1. Methane is lighter than air
  2. Its flammable range is about 5% to 15%
  3. It has a high autoignition temperature
  4. Methane is heavier than air and pools at floor level
WhyMethane's vapor density is about 0.55, so it rises rather than settling low; the claim that it is heavier than air and pools at the floor is false.

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