Quick Answer
Pressure transmitter calibration at Prism uses a dead weight tester (for absolute/gauge pressure) or calibrated reference transmitter as reference standard. The process covers 5 calibration points from 0–100% range, records as-found and as-left data, and issues a NABL CC-2480 accredited certificate.
Key Takeaways
- Pressure transmitter calibration covers gauge, absolute, differential, and vacuum pressure types.
- Dead weight tester (piston gauge) is the primary reference standard for highest accuracy.
- Calibration range at Prism: vacuum (–1 bar) to +700 bar gauge pressure.
- HART trim (sensor trim + output trim) is performed during calibration of smart transmitters.
- Calibration per IEC 60770, manufacturer specs, and NABL CC-2480 accreditation scope.
Types of Pressure Instruments Calibrated at Prism
Gauge Pressure Transmitters
Most common type. Measures pressure relative to atmospheric. Range: 0–700 bar. Brands: Rosemount 3051, Yokogawa EJA.
Differential Pressure (DP) Transmitters
Measures difference between two pressures. Used for flow measurement, filter monitoring, level in tanks.
Absolute Pressure Transmitters
Measures pressure relative to perfect vacuum. Used in altitude, vacuum processes, and HVAC.
Pressure Gauges
Bourdon tube, diaphragm, capsule types. Calibrated with dead weight tester or calibrated reference gauge.
Manometers
U-tube and well-type liquid manometers calibrated for low-pressure measurement (air, water column).
Vacuum Gauges
Pirani, thermocouple, and capacitance vacuum gauges calibrated using calibrated vacuum standards.
Pressure Transmitter Calibration Procedure
Reference Standard Setup
Connect dead weight tester (for high pressure) or precision pressure controller (for low pressure) as reference standard. Reference uncertainty must be ≤ 1/4 of instrument's accuracy.
Zero Check
Vent the transmitter to atmosphere. Record zero reading. Zero error must be < ±0.1% of span for smart transmitters.
Span Check
Apply 100% of rated pressure. Record span reading. Span error must be < ±0.1% of span.
5-Point Calibration
Apply pressure at 0%, 25%, 50%, 75%, 100% of range. Record transmitter output (mA or digital) and reference pressure at each point.
HART Trim (for smart transmitters)
Perform Lower Sensor Trim and Upper Sensor Trim using HART communicator to correct sensor drift.
As-Left Verification
After trim, repeat 5-point measurement to confirm as-left accuracy meets specification.
Certificate Issue
Issue NABL certificate with as-found/as-left data, uncertainty, and HART tag number.
Pressure Transmitter Brands We Calibrate
- Emerson Rosemount (3051, 3051S, 3051CD, 1151)
- Yokogawa (EJA110E, EJA430E, EJX series)
- Endress+Hauser (Cerabar, Deltabar, Deltapilot)
- ABB (266AST, 266PST, 2600T series)
- Honeywell (STD800, STG900, STG7800)
- Siemens (SITRANS P DS III, SITRANS P200)
- Wika, Gems, Keller, Druck (GE)
Frequently Asked Questions
What reference standard is used for pressure transmitter calibration?
Prism uses a dead weight tester (piston gauge) for pressures above 10 bar, a calibrated precision pressure controller for 0.1–1000 bar range, and a digital reference manometer for low differential pressures. All references are traceable to NPL India.
How accurate is pressure transmitter calibration at Prism?
Prism achieves calibration uncertainty of ±0.025% of span for standard pressure transmitters and ±0.01% for high-accuracy DP transmitters — well within 4:1 TUR requirement.
Can Prism calibrate dual-range differential pressure transmitters?
Yes. Prism calibrates DP transmitters with multiple range codes, including suppressed and elevated zero configurations.
How often should pressure transmitters be calibrated?
Annual calibration is standard. Safety-critical transmitters (boiler, pressure vessel, reactor) should be calibrated every 6 months. Newer smart transmitters with SIL certification may have extended intervals if supported by statistical data.
Does Prism issue calibration certificates for pressure gauges as well?
Yes. Prism calibrates Bourdon tube pressure gauges, glycerine-filled gauges, and diaphragm gauges of all makes and ranges, issuing NABL CC-2480 certificates.
Written by
Er. Parthiv Kinariwala
Managing Director · Prism Calibration Centre · NABL CC-2480 · Ahmedabad
Er. Parthiv Kinariwala founded Prism Calibration Centre in 2004 and has over 20 years of hands-on experience in calibration engineering, NABL accreditation, and industrial compliance. His team performs 10,000+ calibrations annually from the Vatva GIDC laboratory, serving 5000+ industries across Gujarat.
Prism Calibration Centre — Vatva GIDC, Ahmedabad
Prism Calibration Centre
F-101, Rudraksh Complex 2, Phase 3, GIDC Vatva, Near Jasoda Nagar Cross Road, Ahmedabad — 382445, Gujarat, India
Phone: +91 98245 26444
Email: info@prismcalibration.com
NABL: CC-2480 · ISO/IEC 17025:2017
Hours: Mon–Sat, 9:00 AM – 7:00 PM