Conductivity paint meter to test sprayability of wet paint

(includes Resistivity Meter 76634-00 and Resistivity Probe 7922-00)

Technical Specifications

Units: MΩ and kΩ

Features

This multifunction meter has two (2) scales, MΩ and kΩ, that can be used to measure paint resistivity. Once the resistivity of the paint has been determined and found to spray successfully, measuring the resistivity with this meter provides a means of duplicating conditions. This is also important when troubleshooting spray or rotary applicator problems.

NOTE: 7922-00 Paint Probe Assembly not sold separately

Applications

Testing and measuring the electrical resistance of paint formulations

Operating Manual

Ransburg 76652-03 Instruction Manual (*.pdf, 397 KB)

What is wet resistivity in paint? And why is paint resistivity important?

Paint resistivity is the most important factor in determining whether the paint formulation is suitable for the electrostatic painting process. By definition, coating resistivity is the degree to which the coating material resists the flow of current. Coatings with a high resistivity may perform poorly. They can usually be reformulated to make them suitable. This does not mean that the resistivity should be as low as possible.

What is an acceptable resistivity range for electrostatic painting?

As a rule of thumb, a resistivity of 20 to 140 MΩ-CM is suitable for most types of electrostatic equipment. The Ransburg Paint Resistivity Meter measures resistivity in megohms (MΩ). To obtain MΩ-CM as required by ASTM D5628, multiply the meter’s MΩ reading by 132 (MΩ-CM = MΩ reading x 132).

It is also important to note that the properties of some coating materials (e.g., metal flakes and coatings containing metal) can change when high voltage is applied, i.e., they may have a high resistivity when measured, but a low resistivity when applied under high voltage.

Is this the same as the Ransburg Gema Paint Resistance Tester?

There is no ‘Ransburg Gema’ paint resistivity meter. Gema specializes in powder coating equipment and is no longer part of the “Carlisle Fluid Technologies” group (Ransburg, Devilbiss, Binks). However, the Ransburg paint resistivity meter is still sometimes used to check the resistance of dried paint surfaces. This may lead to misunderstandings.

What does ITW mean? And what is the difference between the ‘ITW Ransburg’ and ‘Ransburg’ paint resistivity meters?

ITW stands for Illinois Tool Works Inc. In the past, Ransburg was part of the ITW group and therefore ‘ITW Ransburg’ was used as a marking on the tool. This is no longer the case. The same tool now has the ‘Ransburg’ label on it.

Does the size of container influence the measurement readings?

No, it doesn’t. However, it is strongly recommended that the measurements be taken in laboratory glassware and not in a production environment (e.g., from 20 or 200 liter tanks in the factory). The reason: The probe is only allowed to be immersed to a certain depth when taking the reading (see also ‘Maximum Insert Depth for Measurements’ and ‘Warning 1’ and ‘Warning 2’ in the manual). It is not uncommon that the probe accidentally falls into the tank/container causing irreparable damage to the device.

Can the Ransburg Paint Resistivity Meter used even if the electrostatic spray gun is from another manufacturer?

Yes, measuring the resistivity of the paint is a separate process, a step before the actual electrostatic painting. To measure the electrical resistivity of wet paint, Graco offers the 722-886 Megohmmeter Paint Resistivity Meter in combination with the 722-860 Paint Probe. And Wagner offers the RS 500 (2326041) paint resistivity meter, which can be used for solvent-based paints to check their suitability for electrostatic applications.

However, the recommended paint resistance for each spray gun must be checked in the manual for the electrostatic paint gun or device.
For example the recommendations of Wagner are:

• Spray gun model Wagner GM 5000EA: >150kΩ solvent based paints
• Spray gun model Wagner GM 5000EA LowR Version: >50kΩ solvent based paints, incl. metallics
• Spray gun model Wagner GM 5000EAW: 1kΩ.cm to 1MΩ.cm water based paints

OPTIONS:

• 76652-02 Kit for measuring short circuit current (SCI), resistance and sprayability  (incl. 76634-00 Multi-Function Meter, 76664-00 Test Lead Assembly)
• 76652-04 Deluxe Kit (incl. 76634-00 Multi Function Meter, 7922-00 Paint Probe Assembly, 76664-00 Test Lead Assembly, 76667-00 High Voltage Probe Assembly)

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