A pressure number without a gauge identity or unit is difficult to interpret. For a NOV Type P discharge-pressure record, preserve what the instrument displayed and the conditions under which it was observed. This checklist documents an observation; it does not select a gauge, define a safe operating pressure or establish calibration.
Read the OEM mounting note in context
NOV document 25-101131, page 20, describes mounting the discharge pressure gauge at the strainer clean-out flange. That arrangement is explicitly subject to an operating-pressure limitation in the source. Do not apply this mounting note to every Type P installation without checking the applicable equipment documents.
The passage is not a gauge calibration procedure. It does not establish the installed instrument's accuracy, calibration interval or acceptable deviation. The same page discusses a high-pressure relief valve separately; a gauge observation is not evidence that overpressure protection has been tested.
What to retain with an observation
These are editorial record fields, not additional OEM inspection requirements:
- Pump tag, model and serial number, plus the instrument tag or other confirmed identifier.
- Gauge location as identified by the applicable installation document.
- Observation date and time, and the operating state reported by authorized personnel.
- Displayed value and unit exactly as read; identify the scale used if the dial carries more than one.
- Whether the indication was steady, fluctuating or unreadable during the observation.
- Visible instrument identification and any calibration-record reference that was actually checked.
- Observer, safe-view photograph reference where permitted, and any unresolved follow-up.
Do not add decimal places that the display does not support. If a reading is unclear, preserve that uncertainty instead of entering zero. For a fluctuating indication, describe what was observed and the observation period; do not call a single photograph a trend or an average.
Keep range, reading and equipment limit separate
A dial's upper scale marking is its displayed range endpoint, not a recorded operating value and not authorization to operate the pump at that pressure. The applicable equipment limits must come from the approved equipment documents.
When comparing records, check that they concern the same measurement location, unit and operating state. If a converted value is needed, retain the original reading and unit alongside the conversion. A difference between instruments cannot establish which one is correct without an appropriate assessment.
Likewise, a calibration label reference is not a calibration result. If the underlying record was not available, mark calibration status as unverified. This article supplies no pass/fail tolerance and does not prescribe an adjustment or test method.
Handle uncertainty through the operating procedure
An unexpected or unreadable indication should be handled through the site's approved operating and maintenance procedures. Do not loosen a gauge connection, remove a flange or adjust equipment to investigate on the basis of this article. Do not treat a zero indication alone as confirmation that equipment is depressurized.
Any physical work requires authorized personnel and the installed equipment's shutdown, isolation, pressure-release verification and safe-access requirements. No reading in this checklist authorizes continued operation or return to service.
The NOV 12-P-160 and NOV 14-P-220 pages provide equipment navigation, not proof of identical instruments, mounting arrangements or pressure ratings.
Source and scope
NOV, How to Treat Your Type P Triplex Mud Pump, document 25-101131, page 20, Discharge Pressure Gage; checked 8 October 2026, Los Angeles time. The mounting context and its limitation come from this source. Observation fields and record-quality distinctions are editorial guidance. No accuracy, compatibility, stock or delivery claim is made.
FAQ
Does the maximum number on a dial establish the pump's allowable pressure?
No. A scale endpoint is not the equipment's approved operating limit.
Can a reading without a unit be compared reliably with an earlier record?
Confirm the unit and measurement context first; do not assume they are the same.
Does a steady reading prove calibration is valid?
No. Stability of an indication and verified instrument accuracy are different matters.
Does a zero reading prove it is safe to open a connection?
No. Follow the approved isolation and pressure-release verification procedure; this observation record is not clearance for physical work.