Calibration
A machine that runs is not the same as a machine that reads correctly. Calibration establishes what a device is actually delivering or measuring, corrects it where it has drifted, and produces the certificate that proves both, which is what an assessor asks for.
What requires calibration, and how often
| Equipment | Parameter verified | Interval |
|---|---|---|
| Ventilators, anaesthesia workstations | Delivered volume, pressure, FiO₂, flow | Half-yearly |
| Infusion and syringe pumps | Flow rate accuracy, occlusion pressure | Half-yearly |
| Defibrillators | Delivered energy, charge time, ECG trace | Half-yearly |
| Patient monitors, ECG | NIBP, SpO₂, temperature, ECG amplitude | Annual |
| Autoclaves and sterilisers | Chamber temperature, pressure, cycle time | Half-yearly |
| Centrifuges | Speed, timer, temperature | Annual |
| Analysers, pH meters | Against reference standards and controls | Per manufacturer, at least annual |
| Blood bank refrigerators, incubators | Temperature uniformity and stability, alarms | Half-yearly |
| Weighing scales, including infant scales | Mass across the working range | Annual |
| Physiotherapy output devices | Delivered energy or current | Annual |
| X-ray, mammography, CT | Output, kVp accuracy, timer, beam alignment | Annual, with the QA schedule |
Anything repaired in a way that could affect its output is recalibrated before it goes back into service, whatever the calendar says.
How it is carried out
Calibration is done against reference instruments (a gas flow analyser, an infusion device analyser, a defibrillator analyser, temperature and pressure references), each with its own traceable calibration history. A reference instrument that is itself out of date makes every certificate it produced worthless, so ours are tracked as carefully as the equipment they check.
Readings are taken at multiple points across the working range, not at a single convenient setting. A pump that is accurate at 100 ml/hr and wrong at 5 ml/hr has failed where it matters, because 5 ml/hr is a neonate.
Values are recorded as found, adjustment is made where it is needed, and values are recorded again as left. Both sets appear on the certificate. A certificate that only shows the final reading conceals how far the device had drifted, which is exactly the information a biomedical department needs.
Certificates and audit
You receive a certificate per device, a calibration status label on the device itself showing the due date, and a schedule of what falls due when across the fleet.
For NABH assessment and National Health Mission reporting, that schedule matters as much as the certificates. An assessor is checking whether the hospital has a system, not whether one machine happens to be in date. We issue the schedule with the certificates so the department can show both.
Questions about calibration.
Not answered here? Call +91 98250 70790 and speak to someone who works on the equipment.
01How often does hospital equipment need calibration?
Annually for most equipment, and half-yearly for devices whose reading directly drives a clinical decision or a drug dose: infusion pumps, defibrillators, autoclaves and laboratory analysers. Manufacturer intervals take precedence where they are shorter. Any device is recalibrated after a repair that could have affected its output.
02Which equipment actually requires calibration?
Anything that measures or delivers a quantity: ventilators, anaesthesia machines, infusion and syringe pumps, defibrillators, patient monitors, ECG, autoclaves and sterilisers, centrifuges, analysers, refrigerators, incubators, weighing scales and physiotherapy output devices. Equipment that neither measures nor delivers, such as a bed, a trolley or an examination light, does not.
03What is on the calibration certificate?
The device identity and serial number, the reference instrument used and its own traceability, the ambient conditions, the readings taken before and after adjustment, the pass or fail against tolerance, the date, the due date, and the signature of the engineer who carried it out.
04What happens if a device fails calibration?
It is adjusted and retested. If it cannot be brought inside tolerance the device is tagged out of service and you receive a written statement of the deviation found, so the department can decide about repair or replacement. A failed device is never returned to the ward with a certificate.
05Do you calibrate equipment you do not maintain?
Yes. Calibration is available as standalone work, and it is also included in AMC and CMC contracts where the equipment requires it. Hospitals commonly bring us in for calibration ahead of an NABH assessment and keep us for the maintenance afterwards.
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