Why is a plug installed in the external bypass part of a 2 pipe fuel oil pump

• A. To allow oil to return to tank
• B. To block oil flow
• C. To vent oil to atmosphere
• D. To measure pressure

Answer: (A)

In a two-pipe fuel oil pump, there is an external bypass that serves as a circulation path for excess fuel back to the storage tank. This bypass helps regulate pressure and keeps the pump from overheating when the burner isn’t demanding fuel. Installing a plug in the external bypass port establishes and maintains that return path to the tank. By sealing the bypass, the system ensures any extra pump discharge is directed back to the tank rather than continuing to the burner or escaping elsewhere, which keeps the circulating fuel loop safe and stable. The other options don’t fit because they describe blocking flow, venting to the atmosphere, or measuring pressure, none of which describe the purpose of the bypass return path.