Vibration Standards & Safety Flashcards

Which API standard covers machinery protection systems, including proximity probes, keyphasors, and vibration monitors?

Answer: API 670

API 670 specifies machinery protection systems for vibration, axial position, and temperature monitoring.

Per API 670 practice, how should two radial proximity probes at a bearing normally be oriented?

Answer: 90 degrees apart, typically 45 degrees on either side of vertical

X-Y probes are mounted 90 degrees apart, usually at 45 degrees left and right of top dead center, to capture shaft orbit.

What is the standard sensitivity of an API 670 proximity probe system with a typical 8 mm probe?

Answer: 200 mV/mil (7.87 V/mm)

The standard proximity probe system output is 200 mV/mil, or 7.87 V/mm.

Which API standard applies to centrifugal pumps for petroleum, petrochemical, and natural gas industries and includes pump vibration acceptance limits?

Answer: API 610

API 610 covers centrifugal pumps and specifies bearing housing vibration limits in the preferred operating region.

ISO 7919 (now incorporated into the ISO 20816 series) primarily addresses which type of vibration measurement?

Answer: Relative shaft vibration measured on rotating shafts

ISO 7919 provided evaluation criteria for shaft vibration measured on rotating shafts, typically with proximity probes.

Under NEMA MG-1, what is the commonly cited unfiltered vibration limit for standard motors running at 1,200 rpm and above, measured on the bearing housing?

Answer: 0.15 in/s peak

NEMA MG-1 Part 7 sets 0.15 in/s peak as the unfiltered limit for standard motors on resilient mounting.

Why can using a stroboscope near rotating machinery create a safety hazard?

Answer: It can make a rotating shaft appear stationary, tempting someone to touch it

Strobe freezing can create the illusion that a machine is stopped while it is still turning at full speed.