Question

oxygen or fuel gas from a cylinder may only be used through select one. a. approved gas - specific pressure reducing regulator b. a flow regulator c. a manifold unit d. any pressure regulator

Explanation:

Oxygen or fuel gas from a cylinder must be regulated using a gas - specific pressure - reducing regulator. This is because different gases have different pressure requirements and characteristics. A flow regulator (b) is more about controlling the flow rate rather than reducing the pressure from the high - pressure cylinder. A manifold unit (c) is used for connecting multiple cylinders, not for pressure reduction. And using any pressure regulator (d) is incorrect as it may not be suitable for the specific gas (oxygen or fuel gas) in terms of pressure reduction and safety.

Answer:

a. Approved gas - specific pressure - reducing regulator