In this guide 6 sections
A sensor datasheet states what the device measures, how it reports the value and where it can be installed, covering range, output type, thread and enclosure rating. A calibration certificate shows how one serial number performed against a reference instrument on the test day, and linking it to the batch lets any queried reading be traced.
Read the datasheet in four passes
A datasheet looks dense. You only need four answers at first: what does it measure, over what range, how does it send the result and where can it be installed? Everything else is detail for the engineer.
Range deserves a closer look. A pressure transmitter rated for a narrow span reads well inside it and poorly near the edge, and customers order the wrong span because two part numbers look alike.
Sales staff need no memorised tables. They need a stock record that carries the key fields, so each quote lists the right transmitter with the correct span, thread and output. Fewer returns follow soon.
- Measured quantity and unit
- Range and accuracy class
- Output type and supply voltage
- Process connection and thread
- Enclosure rating and temperature limits
Output types explained
Output is how a sensor talks. A 4-20 mA loop is common for process sensors because a broken wire shows as zero current, while a 0-10 V signal is simpler but noisier over distance.
Switching sensors usually give a PNP or NPN output, and the wrong pairing with a PLC input card means the sensor never signals. Digital links such as IO-Link or Modbus carry more data, including diagnostics, which helps a service engineer find a failing unit before the line stops. Low-voltage analogue signals pick up noise from drives and welders, so cable routing and shielding often decide whether a reading stays stable on a busy shop floor.
Keep output as a searchable stock field. Someone who asks for an alternative wants the same output as well as the same range, because a different signal means new wiring or a new input card.
What an IP rating tells you and what it does not
An IP rating has two digits. The first digit speaks of dust and solid objects, the second of water, and a higher number means better protection against that one hazard only. It says nothing else.
A sensor with a good water rating can still fail from chemical washdown, steam or vibration; read the notes under the rating for the conditions of the test.
Record the rating beside the product and ask the customer where it will sit, because a dairy washdown and a dry warehouse call for different items. Seals, glands and mounting all count.
Calibration certificates: what the fields mean
A certificate belongs to one unit. It names the serial number, the date, the reference instrument used, the test points and the measured error at each point, so two units of one model stay separate. Some also show as-found and as-left readings.
Look for the due date and the stated uncertainty, because a certificate with no reference to a traceable standard is only a factory test sheet. Customers in food, pharma and power plants will ask which of the two you hold, so know the answer before the audit.
Scan every certificate and attach it to its serial number the day it arrives, since a folder of PDFs named by date fails at the first query. The habit costs a minute per unit. It saves an afternoon of searching.
- Serial number and model
- Reference instrument and its own due date
- Test points with measured error
- As-found and as-left values
- Calibration date and next due date
Why batch traceability matters when a reading is queried
Suppose a level sensor drifts. You need to know which batch it came from, which supplier lot, which calibration run and which invoice sent it out, and without that chain you can only guess. One chain, one place.
Record the batch at goods receipt, scan the serial on dispatch and link both to the customer order, so that a query takes minutes instead of days. Buyers of the same lot get warned.
Try this check today. Pick one sensor you sold last month and time your search for its certificate, the batch record and the dispatch note together.
Sensor record sheet
The sheet has three parts. Part one holds datasheet fields from quantity and range to thread and enclosure rating, and part two holds serial, date, reference, test point errors and due date. Part three holds the trace chain of supplier lot, goods receipt, customer order and dispatch date, so any reading can be followed back to its source.
Open a blank worksheet to printQuestions owners ask
Is a calibration certificate the same as a datasheet?
No, they are different documents. A datasheet describes the whole model. A calibration certificate describes how one serial number performed against a reference on a given date, so you often need both.
How often should a sensor be recalibrated?
It depends on the duty, the drift seen between calibrations and the customer’s quality rules, with the certificate stating a due date. The customer’s procedure usually sets the cycle.
Why do some customers ask for traceable calibration?
Audits in regulated industries such as food, pharma and power generation require evidence that a measurement can be linked to a recognised standard. A factory test sheet may fall short.
What should a supplier store with each sensor sale?
Store the serial number, batch or lot, the certificate PDF, the order number and the dispatch date, since that set answers most reading queries without searching old email.