Sensistor Leak Detectors by INFICON

The XRS9012 has 10 sensitivity levels; the highest, extremely sensitive levels help to identify suspect areas faster. However, a decision to excavate should only be made once the leak has been reconfirmed at level 5 or lower. If the signal is too weak, wait until the gas concentration increases or make a few holes for higher signals. Excavate only on signals that can be repeated over and over again.

Procedure:

1. Establish the location, diameter and length of the pipe, empty the pipe and isolate the section to be tested.
2. Inject the tracer gas at low pressure (0.5 to 1 bar) at one end and release it at the other; measure at the far end to check that the gas has reached the entire length.
3. Wait until the gas from the leak has risen to the surface.
4. Walk the pipe with the XRS9012 and the hand probe extension, stopping approximately every 50 cm to draw a new sample; sound and LED indicators guide you to the leak, typically to within ±1 m.

The method is suitable for distribution and service pipes up to 30 cm in diameter; on pipes in service, filling takes longer and the leak shows at the surface with a delay.

The XRS9012 gives off a pulsating acoustic alarm and the ON lamp blinks red when an error is detected. The lit LEDs indicate the cause:

• LED 1 and LED 4 together: the cable or the probe is most likely not connected.
• LED 1, 2, 3 or 4 alone: the cable or the sensor is most likely broken (LEDs 1 and 2 indicate low or high sensor temperature, LEDs 3 and 4 low or high sensor voltage).
• LED 8: the battery voltage is below 5.0 V and the instrument needs to be charged.

The H21 hand probe is the standard accessory of the XRS9012, with the sensor at the probe tip; it is connected via the C21 probe cable with a length of 3, 6 or 9 m. For MAX mode, which compares the gas concentration at several test points, the H21 is suitable for measurements under manhole covers and the 8612 surface probe for measurements on manhole covers and hard toppings.

SEARCH mode is used to pinpoint the leak: the pitch of the signal rises as you approach the leak and falls as you move away. MAX mode compares the gas concentration at several points, e.g. under manhole covers, and helps to pre-locate leaks after a longer section has been filled with tracer gas. Place the probe and press MAX; the instrument measures for 10 seconds and then shows the reading. For comparable results, the probe must be placed in the same way at every point, and the sensitivity can only be changed in SEARCH mode.

This depends strongly on the soil type, the surface and the depth of the pipe. Guide values:

Actual times can vary significantly depending on ground and pipe conditions.

Specifications:

The cable or pipe under test is filled with forming gas consisting of 5% hydrogen and 95% nitrogen. At a leak, the tracer gas escapes and is detected by the hydrogen sensor, which on the XRS9012 is located at the tip of the probe. The sensor relies on diffusion and responds selectively to hydrogen. Applications include pressurized telecom cables (buried or ducted), water and gas pipes, gas-filled power cables and heating systems.