MKS HPS 937A Series Owner's Operation And Maintenance Manual page 15

Do not operate in explosive environments.
To avoid explosion, do not operate this product in an explosive environment
unless it has been specifically certified for such operation.
Service by qualified personnel only.
Operating personnel must not remove instrument covers. Component
replacement and internal adjustments must be made by qualified service
personnel only.
Use the proper power cord.
Use only a power cord that is in good condition and which meets the input
power requirements specified in the manual.
Use only a detachable cord set with conductors that have a cross-sectional
area equal to or greater than 0.75 mm
by a qualified agency such as VDE, Semko, or SEV.
2 . The power cable should be approved
937A Multi-Sensor System
7