ASTM D2624 Conductivity Meter – Jet fuel

Digital fuel conductivity meter for aviation safety

The Emcee Model 1152 is a digital fuel conductivity meter designed to provide convenient, reliable and accurate measurement of electrical conductivity in fuels and other liquids. It reads in conductivity units (CU), where one CU is defined as one picosiemen per meter, in accordance with ASTM D2624.​

Hydrocarbon fuels such as jet fuel and diesel typically exhibit very low electrical conductivity and therefore have a tendency to retain static charge, particularly when pumped at high flow rates or passed through filters. The Model 1152 portable fuel conductivity tester measures the ability of these fuels to dissipate static charge, supporting safer loading, transfer and refuelling operations for aviation and industrial users.​

Measurement principle and ASTM D2624 alignment

The Model 1152 consists of a compact electronics assembly and a detachable stainless steel probe that acts as a two-electrode cell with concentric electrodes. When the probe is immersed in the fuel to a defined depth, a constant direct voltage is applied, producing a small current through the liquid that is proportional to its electrical conductivity.​

The current is amplified and displayed digitally as conductivity in picosiemens per meter, which is equivalent to conductivity units as used in ASTM D2624. The standard Model 1152 digital conductivity range covers 0 to 1999 pSm in 1 pSm steps, providing fine resolution for aircraft fuel conductivity meter measurements in typical aviation and distillate fuels.​

Portable design for field and laboratory use

This portable fuel conductivity meter is a handheld, battery-powered instrument suited to both laboratory bench testing and field use around storage tanks, tank farms and tanker trucks. The electronics are housed in a rugged cast aluminium case with solvent-resistant coating, designed to withstand regular handling in fuel depots and on airport aprons.​

A detachable stainless steel probe connects directly to the instrument or via an accessory cable reel kit, which provides a 50‑foot (approx.) cable and a grounding lead for safe measurements in large tanks. This configuration allows users to deploy the probe deep into storage tanks while keeping the aviation fuel tester conductivity display in a convenient safe location.​

Display, controls and self-check calibration

The Model 1152 digital conductivity meter uses a large three‑digit liquid crystal display with characters approximately 0.27 inches (7 mm) high for clear visibility in varied lighting conditions. Two front-panel pushbuttons provide simple operation: one for MEASURE and one for CALIBRATE.​

A straightforward self-check routine allows the operator to verify zero and calibration without external standards. With the probe out of the fuel, pressing MEASURE after a short stabilisation time should display 000–001, confirming zero. Pressing CALIBRATE with the probe in air should produce a reading equal to ten times the individual probe calibration number within a small tolerance, verifying the calibration circuit. If either check is outside limits, internal zero and calibration adjustments are available using the built-in controls.​

Range, precision and repeatability

The standard Model 1152 aviation fuel tester conductivity configuration covers 0–1999 pSm with 1 pSm resolution and a specified electrical calibration accuracy of approximately 1–2% of reading. Because fuel behaviour contributes to overall measurement performance, the instrument’s repeatability and reproducibility have been characterised through round-robin testing over the 0–2000 pSm range.​

Illustrative limits show that at 50 pSm the repeatability is about 4 pSm and reproducibility about 12 pSm, increasing gradually with conductivity up to 400 pSm, where repeatability and reproducibility are approximately 5 and 10 pSm respectively at room temperature. These data provide confidence that the portable fuel conductivity tester can reliably track changes in fuel conductivity relevant to static dissipater additive treatment, filtration effects and fuel handling conditions.​

Intrinsic safety and hazardous area use

The Model 1152 is designed as an intrinsically safe aircraft fuel conductivity meter for use in hazardous locations when installed and maintained as specified. It carries approvals from Underwriters Laboratories (UL), the Canadian Standards Association (CSA) and LCIE, subject to strict adherence to the specified battery type and enclosure condition.​

Intrinsic safety depends on the aluminium case maintaining its protective polyurethane coating and on using only three Energizer A544 6 V alkaline batteries. Substitution of components, use of other battery types or operation with damaged coating may impair intrinsic safety and invalidate approvals.​

Power supply and battery management

The unit operates from three readily available 6 V alkaline batteries, located in an internal battery housing accessible from the rear of the instrument. An internal battery checking circuit monitors supply condition; if batteries become weak the meter will power briefly and then shut down, and if voltage is too low the unit will not turn on.​

Battery replacement must never be attempted in the presence of an explosive atmosphere. After replacing batteries, operators should confirm zero and calibration using the built-in procedures before returning the portable fuel conductivity meter to service.​

Sample handling and good measurement practice

To achieve representative aviation fuel tester conductivity results, sample containers should be clean, typically a one‑litre metal container washed with suitable solvent and rinsed with the fuel under test. After filling, allowing approximately two minutes before measurement permits transient charges induced during sampling to dissipate.​

During the test, the probe is immersed in the fuel up to the upper vent holes and the MEASURE button is pressed, with the correct reading taken after about three seconds. Because polarisation effects cause the indicated conductivity to drift with time, only this defined three‑second reading is used as the reportable value.