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I just recently bought one of your liquid filled tire gauges, and it seems to be off by 2-3psi.
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Staff
replied three years ago
The Motion Pro Tire Gauges are all rated to 1.5% of scale for accuracy, which translates to 0.9psi in the 0-60 psi gauge. All of our gauges are tested here before shipment, and the majority of gauges test within 0.2 psi of actual. Unless the gauge you have was dropped or damaged by over pressurization, it should still have that same accuracy.
A detail you may not be aware of is that with a liquid filled gauge such as we use, the case needs to be balanced to current ambient atmospheric conditions to achieve its greatest accuracy. All Bourdon tube analog dial gauges reference atmospheric pressure for zero. A standard non-liquid filled gauge is always vented to atmosphere, and so is always referencing current conditions as it's zero. If a liquid filled gauge is in a stable environment where conditions are always the same (for instance in a stable temperature shop), simply piercing the seal should be adequate. However, if you are using the gauge in varying conditions, i.e. at the shop and the track, there is an additional step to be taken to ensure total accuracy. Varying conditions will cause the pressure inside the case to be different from outside ambient pressures, and so needs to be balanced to atmosphere periodically to accurately zero. The procedure for doing this should be performed directly before reading a pressure. The boot is pushed back on the gauge, exposing the seal at the top of the gauge body. Holding the gauge vertically, so that the liquid is not spilled, you open the seal partially at the top of the body to vent and balance the gauge to atmosphere. Replace the seal and the boot, and the gauge is ready to take a pressure reading. As an extreme example, if your gauge was stored in a shop at 65 degrees, and you went to a track to ride, and left the gauge in the sun for three hours before using it, the pressure inside the gauge will be much higher than outside atmospheric pressure. If this is not corrected, the pressure differential could affect the accuracy of the gauge by as much as 10-15% of range. Venting the gauge before use as described will eliminate this problem.
A detail you may not be aware of is that with a liquid filled gauge such as we use, the case needs to be balanced to current ambient atmospheric conditions to achieve its greatest accuracy. All Bourdon tube analog dial gauges reference atmospheric pressure for zero. A standard non-liquid filled gauge is always vented to atmosphere, and so is always referencing current conditions as it's zero. If a liquid filled gauge is in a stable environment where conditions are always the same (for instance in a stable temperature shop), simply piercing the seal should be adequate. However, if you are using the gauge in varying conditions, i.e. at the shop and the track, there is an additional step to be taken to ensure total accuracy. Varying conditions will cause the pressure inside the case to be different from outside ambient pressures, and so needs to be balanced to atmosphere periodically to accurately zero. The procedure for doing this should be performed directly before reading a pressure. The boot is pushed back on the gauge, exposing the seal at the top of the gauge body. Holding the gauge vertically, so that the liquid is not spilled, you open the seal partially at the top of the body to vent and balance the gauge to atmosphere. Replace the seal and the boot, and the gauge is ready to take a pressure reading. As an extreme example, if your gauge was stored in a shop at 65 degrees, and you went to a track to ride, and left the gauge in the sun for three hours before using it, the pressure inside the gauge will be much higher than outside atmospheric pressure. If this is not corrected, the pressure differential could affect the accuracy of the gauge by as much as 10-15% of range. Venting the gauge before use as described will eliminate this problem.