Testing ionisers: the Desco 19433 Verification Kit

Why ionisers need regular testing

An ioniser works quietly in the background. That is why nobody notices when it drifts out of balance or removes charge too slowly. Only a measurement shows either.

Two values are measured for verification: the offset voltage (balance), which shows whether the ioniser delivers positive and negative ions in equilibrium, and the discharge time, meaning how quickly it removes an applied charge.

An ioniser that has drifted out of balance can itself place a charge on sensitive components or assemblies. Desco therefore points out that ionisers should be checked regularly for offset voltage and discharge time.

What ANSI/ESD SP3.3 and ESD TR53 provide

ANSI/ESD SP3.3 describes the periodic verification of ionisers, ESD TR53 the compliance verification of ESD protective equipment. Both use the same two measurements: offset voltage and discharge time.

According to SP3.3, each ioniser is tested in its normal operating configuration. In general this applies to all ionisers, not just a sample. The measurements should already be taken at acceptance so that a baseline exists for later comparison. The aim is to detect a significant change in performance.

The Desco Ioniser Verification Kit 19433

The Desco Ioniser Verification Kit 19433 contains everything needed to measure the offset voltage and discharge time of an ioniser right at the workstation, without removing the unit.

• Static field meter 19432 with a measuring range up to ±40.0 kV
• Conductive plate made of aluminium for offset voltage and discharge time
• ±1000 V charger, brings the plate to test voltage
• USB-C charging cable (1 m) for the field meter battery
• Carrying case made of polypropylene with foam insert

The kit is NIST traceably calibrated, made in the USA and suited to checking benchtop, overhead and compressed air ionisers in ESD protected areas.

How testing with the kit works

The procedure follows the Desco operating instructions TB-3106: attach the plate, measure the balance, then time the discharge for both polarities.

The plate is slid onto the field meter and the device switches to conductive plate mode (CPM). The operator must be grounded, because the field meter is grounded through the operator's hand, and the charger also only works with a grounded operator.

• Offset voltage: hold the field meter with the plate so that the ionised airflow reaches the plate. The display shows the offset voltage (balance).
• Positive discharge time: charge the plate with the charger to more than +1000 V and use a stopwatch to time how long the voltage takes to fall from +1000 V to +100 V.
• Negative discharge time: the same with a negative charge, from -1000 V to -100 V.
• Document: record the results and compare them with the specification and the baseline.

Between tests, keep the insulators of the plate clean so that surface leakage does not distort the result. According to Desco, the 9 V battery in the charger should be replaced once a year.

Field meter 19432, holster 19434 and video tutorials

Beyond ioniser testing, the field meter in the kit also measures charges on insulators and is available separately. A matching belt holster is available for inspection rounds.

The Desco static field meter 19432 measures 0 to ±40.0 kV with polarity display. A time-of-flight sensor detects the distance from 1 to 200 mm and corrects the reading automatically. Snapshot hold freezes the value as soon as you pull the device away from the object, 10 readings can be stored and read out via USB-C.

The nylon belt clip holster 19434 protects the field meter from bumps and scratches and keeps it within reach on your belt, leaving both hands free between measurements.

Frequently asked questions