Martel Electronics BetaGauge 3II - Manual (Page 186)

D-1 Service Information
D-Service Information
Service Schedule
Martel recommends that you return the following
equipment for re-calibration and/or re-certification as
follows:
Equipment Service Schedule
Calibrators Not required
DC Modules Once yearly
Pressure Modules Once yearly
NOTE: Martel calibrates and certifies according to
precision standards that are traceable to the
National Institute of Standards and
Technology.