Final answer:
Dichloromethane (CH₂Cl₂) is the trace refrigerant commonly used for leak checking in refrigeration systems. It can be detected by a mass spectrometer attached to a high-vacuum pump. Other refrigerants like HFCs and HCFCs can also be used.
Step-by-step explanation:
The trace refrigerant commonly used for leak checking is dichloromethane (CH₂Cl₂).
Dichloromethane, also known as methylene chloride, is a solvent that is used to check for leaks in refrigeration systems. It is often used as a substitute for carbon tetrachloride, which is toxic and carcinogenic. When injected into a compartment of a refrigeration system, any leaks can be detected by a mass spectrometer attached to a high-vacuum pump.
Other common refrigerants such as hydrofluorocarbons (HFCs) and hydrochlorofluorocarbons (HCFCs) like HFC-134a and HCFC-141b can also be used for leak checking.