Liquid Level Indicator
The PLI-1 Portable Liquid Level Indicator is designed to offer a rapid and reliable method of determining the liquid level of CO2, Halon and replacement gases.
- Negates the need to remove and weigh cylinders.
A complete PLI-1 kit includes:
- Carry case
- Couplant
- 1.5m Cable and Sensor
- Three-section telescopic extension rod (optional)
- Protective Leather Pouch (optional)
Left: Magnets holding sensor to cylinder and optional leather case incorporating neck and waist strap for hands-free use.
Right: Optional extension arm facilitates testing of inaccessible multi-bank cylinders
| Method of Operation | The Sensor | The Level Indicator |
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Theory of Operation
The sensor generates an ultrasonic sound wave with a centre frequency of 1MHz.
The pulse repetition frequency is continuously modulated to counter signal phase cancellation originating from the complex signal waveform. The cylinder wall generates a complex harmonic waveform from the longitudinal component of the sound beam. This is mixed with the signals arriving from the far side of the cylinder, having travelled directly through the liquefied gas. To this signal is added the response of the sound that has travelled around the steel cylinder. This signal is itself, a complex waveform made up of shear waves refracted into the steel and surface waves generated at the inner surface of the cylinder. As the sensor is moved vertically along the cylinder to be positioned at the interface of the liquid/gas yet more propagation modes are generated.
The significance of the various modes of sound propagation lies in the differing transit times of these types of sound beam. The instrument compares these differences and the absence or presence of one or more of these components in the composite signal is the key factor in determining the liquid level.
| Liquid-Level Specification: | |
| Display type: | 10 Segment Analogue Meter |
| Back Light: | White LED |
| Size: | 200 x 100 x 40mm(max) |
| Weight: | 300g |
| Sensor: | 1MHz 10mm |
| Length: | 95mm |
| Diameter: | 60mm (max) |
| Batteries: | 2 x 9Volt (PP3 type 6F22) |
- Suitable for high or low pressure CO2, Halon or FM200
- Ultrasonic single crystal probe sensor and magnetic clamp for hands free use.
- Accuracy +/- 1.5mm
- Can be used on cylinders, pipe-work and any single skinned holding vessel up to 25mm thick walls.
The instrument has only two controls for ease of operation. The GAIN control allows adjustment of the ultrasound response to accommodate different cylinder sizes, gas type and cylinder condition. The main function selector switch controls off/on/battery check/gain boost.