Dewpoint sample systems

Our dewpoint sample systems extract, condition, and analyse representative samples of process air or gas, which are then safely vented back into the atmosphere or returned to the process line.

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How our dewpoint sample systems work

Dewpoint sample systems are sophisticated analytical tools designed to measure the amount of moisture in gases, particularly in industrial processes where moisture levels are critical to system performance and product quality.

These systems work by extracting a small sample of gas from the main process line and conditioning it to ensure it is clean and at the correct pressure and temperature for accurate dewpoint measurement. This involves the use of filters to remove particulates and condensate, and regulators to adjust the pressure of the gas sample.

Once conditioned, the sample is passed over a dewpoint sensor within the system. This sensor is designed to detect the temperature at which moisture present in the gas begins to condense, known as the dewpoint. This measurement is crucial because it indicates the amount of moisture the gas can hold before it reaches saturation and begins to condense, which can lead to issues such as corrosion, bacterial growth, or system inefficiency.

The output from the dewpoint sensor is then typically displayed on a digital hygrometer, providing real-time, accurate moisture readings. Advanced systems may include options for remote monitoring and data logging, enhancing the functionality and application range of the system in complex industrial setups.

Key Applications

AerospaceProduction of extremely high-specification aeronautical parts can require vacuum furnace heat treatment using very dry argon. NADCAP standards also specify testing welding shield gas at the torch head to ensure dryness. Continuous measurement of trace moisture ensures that the feed gas used for shielding remains within the specified moisture content range, allowing operators to maintain ideal conditions.

Breathing AirHigh levels of moisture in breathing air make it uncomfortable to breathe and pose a potential health risk due to the increased risk of bacteria. High humidity levels in compressed air for breathing apparatus pose a higher risk of moisture condensing, causing blocked airlines or corroding cylinders. Continuous monitoring of trace moisture is therefore necessary throughout the pipe network.

Food and BeverageIncorrect levels of moisture in foodstuffs can lead to loss of food quality. The shelf life of foods packaged in plastic can be extended by replacing ambient air with very dry gases such as Nitrogen and carbon dioxide between the foil layer and the food. The continuous measurement of trace moisture can significantly reduce waste and carbon footprint.

HDPE ProductionEthylene and propylene are perhaps the two most important compounds used in industry today, acting as building blocks for manufacturing a wide range of chemicals and plastics. Accurate and consistent measurement of trace moisture will help with process optimisation, prove gas product quality and polymerisation yield, and reduce corrosion in pipelines and maintenance costs.

Injection MouldingMoisture adsorbed on the surface of plastic pellets that feed injection moulders can cause extrusion failures, decreasing the strength of the product and affecting its surface finish, colour and opacity. Dry air circulates through the pellets, removing moisture, and ensuring they are dry. Increase process efficiency and decrease costs by measuring trace moisture to detect any failure of the dryer.

Medical GasesThe compressed air and gases used for patient care in medical applications need to be clean and almost sterile. Contaminants can be harmful to the health of patients if they are not controlled. Condensation in gas systems may result in interference with critical apparatus, leading to corrosion. The warm temperatures in hospitals, coupled with high humidity risk bacterial growth. HTM02, the Health Technical Memorandum, recommends that “all medical gas supplies should be continuously monitored for dew point or moisture content” in the air/gas line.

Natural Gas and LNGLiquification and regasification of natural gas have become integral and vital to the supply of global energy. The presence of moisture in the transportation of natural gas poses significant challenges, including the risk of freezing in vital pipelines and valves. Ensuring accurate measurement of trace moisture ensures gas quality, protecting downstream systems and extending the functional longevity of desiccant materials.

PharmaceuticalsExcessive or deficient moisture content can impact the physical properties of a pharmaceutical product, affecting the product’s chemical reactivity, binding properties and shelf life. Moisture content fluctuates from batch to batch, so a reliable method is required to determine accurate moisture content and achieve consistency. The trace moisture measurement instrument must be fast, repeatable and accurate for continuous online dewpoint control of blanketing gases.

Power GenerationEnsuring the safe, clean and efficient production of energy is a key concern for all energy producers. New technologies and legislation are forcing changes and development in the production and supply of energy. Monitoring and measuring trace moisture will protect your equipment, reduce costs and improve efficiency.

Welding GasesWelding takes place in an atmosphere shielded by inert gases and different welding jobs require various inert gases. Monitoring oxygen levels is key to producing high output and superior weld seams. By continuously measuring moisture, the feed gas used for shielding remains within the specified moisture content range, allowing operators to maintain ideal conditions for welding.

Natural Gas TransferPacked joints are widespread in gas distribution networks but they have the drawback of occasionally allowing moisture ingress, which can spread through the gas distribution system. Thereby resulting in the pilot light failure in domestic appliances. Monitoring/spot-checking trace moisture across a problem area will ensure that the source of the ingress is rapidly identified and fixed.

SF₆ Circuit BreakersSF6 is used for insulation and arc quenching in circuit breakers. Excess moisture promotes arcing which decomposes SF6 into corrosive products, potentially taking the switch out of service and interrupting the power to the distribution network. Current regulations forbid venting SF6 into the atmosphere. Monitoring trace moisture in conjunction with a Gas Collection and Transfer Unit (GCTU) is ideal for sample analysis before returning to the switch.

Speciality GasesBottled gases certified for use as “calibration gases” must often specify the trace moisture content along with other contaminants. Therefore, suppliers and users need accurate measurements of this moisture level so that much less of the valuable product is expended in the test process.

Whatever the challenge, you can rely on Alpha Moisture Systems

If you require a customised trace moisture measurement solution, book a consultation with our expert technical team and find out how you can increase the efficiency and productivity of your operations.

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