What is the quality of your compressed air? Is Dry, Dry Enough?

Prevent damage with Compressed Air Dew Point control

The modern production technology needs compressed air. The diversity of application starts with non-processed blast air to absolute dry, oil free and sterile compressed air. Irrespective of how it is used, compressed air has to be dry. Depending on the application considerable economical damage can be caused by uncontrolled humidity irruption into the compressed air system.

Compressed air dew point monitoring online refers to the process of continuously measuring and monitoring the dew point of compressed air through an online monitoring system. The dew point of compressed air refers to the temperature at which moisture in the air begins to condense, and it is an important indicator of the moisture content of the air.

Excessive moisture in compressed air can cause several problems, such as corrosion, bacterial growth, and decreased efficiency of downstream equipment. For these reasons, it is important to monitor the dew point of compressed air and keep it within acceptable limits.

Online dew point monitoring systems typically use sensors and control systems to track the dew point of compressed air in real-time, and provide real-time data on the moisture content of the air. These systems can alert operators to any deviations from acceptable limits and provide continuous monitoring of compressed air dew point, allowing facilities to quickly identify and address any issues related to moisture content.

By monitoring the dew point of compressed air online, industrial facilities can ensure that the compressed air remains free of excessive moisture, which can help prevent equipment problems and improve the overall efficiency of the compressed air system.

Reasons that can lead to an increased pressure dew point value within the compressed air system

• Condensate at the refrigeration dryer (condensate eliminator faulty or dirty)
• Condensate overload of the refrigeration dryer
• Adsorption agent is not regenerated sufficiently
• Compressed air bypass in the bypass (valve faulty or not closed)
• Compressed air bypass in the refrigeration dryer (worn out, corroded etc.)

Water in compressed air leads to damages

• Corrosion within the pneumatic plant – Rust will develop in the ducts and functioning elements and will lead to leakages.
• Breakage of the lubricating film – Broken lubricating films lead to mechanical faults.
• Building of electric elements.
• Formation of ice in the compressed air system – At low temperatures the water within the compressed air system could freeze and cause frost damage, reduction of the diameter and blockades.
• • Material handling – High humidity leads to conglutination of materials to be transported, e. g. sugar, concrete, granulate, etc.
• Pharmaceutical – High humidity impairs powders, tablets, etc.
• Hospital – DIN 13260, EN 737-3, danger of bacteria development

The high quality standards in industry require the continuous monitoring of humidity with results which are reliable and invariable over a long period.

We provide stand-alone units or sensors with analogue output that can be integrated in to a centrally controlled system.

Sigma 211 series Dew point sensors with display

Sigma 211 provides reliable and long term stable dew point monitoring in industrial applications, with a range of -60 … +20 °C Td. It makes it an ideal choice for dew point measurements in desiccant dryers.

The new generation of the dew point sensors offering compressed air users a plug & play solution to monitor their compressed air quality according to the ISO 8573-1.All transmitter models are available with 2-wire or 3-wire analog 4… 20 mA output signals, in addition to that the models are available with a Modbus/RTU digital interface. By offering different output signals users can profit from great flexibility and seamless integration into their process.
Additionally the dew point sensors are offered with an integrated pressure sensor, combining a pressure and dew point sensor into a single instrument. The optional OLED display directly mounted on the sensor provides on-site real time values. The display can be easily rotated by 340 ° to fit in any application.

The main body is made from high class aluminium alloy with a soft finish. The process connection is a 1.4301 (SUS 304) stainless steel connection, made to last forever. Top cover made from aluminium at the same quality as the main body. The optional display cover is made from robust Polycarbonate with ABS reinforcement to withstand the rough environment.The new generation are the successors of the well known previous dew point sensor, which have satisfied users for many years.

The new sensors have been redesigned from ground up, integrating the latest technology and all our experience, still they are fully backwards compatible to existing installations.

Features
• For Desiccant Dryers with a measurement range of -60 … +20°C Td.
• Compact size makes them ideal for dryer installations.
• Optional display for on-site values.
• Display can be rotated by 340° to fit your needs.
• User friendly signal outputs: 2-wire analog 4… 20 mA or 3-wire analog 4…20 mA + Modbus/RTU.
• IP65 casing provides robust protection.
• Low maintenance costs due to stable and reliable measurements which increase calibration intervals.
• Measured values available in several units: °C Td • g/m³ • mg/m³ • ppmv • g/kg (@ reference pressure) • % RH.

Sigma 212 Dew point sensor (-50 … +20° Ctd )

Sigma 215 Dew point sensor

Ideal and reliable sensor for  refrigerant dryers.

-20 – +50°C, measuring chamber, with M12 connector (straight type)

The Sigma 215 Dew point sensor provides reliable and long term stable dew point monitoring in industrial applications. With these new models dew point measurement in refrigerant dryers becomes affordable and can replace traditional temperature measurement which often couldn’t tell the real dew point. Η215 outputs the measurement value through the loop powered 4-20 mA signal.

Features
• Affordable dew point sensors for mid-range applications such as refrigerant dryer monitoring
• Long term stability
• IP65 casing provides robust protection in rough industrial environment
• Very fast response time ensures safe and reliable indication whenever dew points are out of valid ranges
• Can be installed directly into dryers through G 1/2″ thread
• High accuracy of ±2 ºC dew point

Sigma 220 Dew point sensor

 -100 … 0 ºC, G 1/2” thread, 16 bar, 1 x 4…20 mA.

Sigma 220 Dew point sensor provides reliable and long term stable dew point monitoring in industrial applications. Sigma 220 is using a new sensor technology which has superior signals at very low moisture levels thus providing reliable measurements down to –100 ºC.

A stainless steel mesh filter with pore sizes below 1 um protects the sensor from particles. It’s designed for applications where very low moisture levels needs to be detected.

The measured dew point is output through a 4-20 mA signal (3-wire or loop powered). Sensor parameters such as analogue output scaling, physical units, can be easily changed by using a service kit.

Stated accuracy under following conditions:

• Ambient temperature 23 +/- 3 ºC
• Process temperature 23 +/- 3 ºC
• Ambient humidity <95%, no condensate
• Airflow > 1 l/min at sensor tip

Features

• Small size makes it ideal for dryer installations
• Measures dew points down to –100 ºC
• New sensor technology
• Version with integrated pressure measurement
• Various output versions available: 1 x 4…20 mA, 2 x 4…20 mA, RS-485 (Modbus), 4…20 mA loop powered
• Very fast response time ensures safe and reliable indication whenever dew points are out of valid ranges
• IP65 casing provides robust protection in rough industrial environment
• Can be installed directly into dryers through G 1/2” thread
• High accuracy of 2 ºC dew point
• M12 connector

Sigma 220 is powered by a current loop, and three wires.

Sigma 305 Dew Point Monitor -50 … +20°C Td and -20 … +50°C Td

100 … 240 VAC or 24 VDC

Refrigerated-Dryers are among the most used dryers in compressed air. Many of these dryers are not performing as intended, too often a lack of maintenance and quality issues result in very high dew points and water in the pipes. In other words: Energy is used for nothing. The dew point indicator at the dryer is not really measuring the dew point but the evaporation temperature. Only the “real”dew point measurement of the outlet air provides reliable results.

The All-In-One solution allows a convenient and price attractive dew point monitoring of refrigerated dryers. Alarm indications offer a timely maintenance avoiding costly system shut downs.

Under normal operation conditions Η305 can be used for 2 years without any re-calibration.

Stated accuracy under following conditions:
• Ambient temperature 23 +/- 3 ºC
• Process temperature 23 +/- 3 ºC
• Ambient humidity <95%, no condensate
• Airflow > 1 l/min at sensor tip

Technical information

Α red light and buzzer alarm, wall mountable version is also available.

The unit is using the relay outputs of Sigma 305 to trigger the alarm

Sigma 230 / 231 Compressed Air Dew Point Transmitters for Ex Applications
(-100… +20 °C Td / -50 … +20 °C Td)

Sigma 230 / 231 Heavy-Duty Dew Point Transmitters provide reliable, long-term stable dew point monitoring for compressed air and gases in harsh and hazardous applications. The fast response time ensures safe and reliable indication whenever dew points are out of valid ranges
S230 For Low Dew Point Applications

The S230 Dew Point Transmitter provides accurate results of a range down to -100 °C Td. This makes it perfectly suitable for special applications where a low dew point needs to be measured. S231 for Standard Range Applications

S231 Dew Point Transmitter comes with a standard range from -50… +50 °C Td, offering a wide range of dew point monitoring applications for compressed air and gases.
Ex Areas Solution

The optional IECEx approval makes it the perfect tool to be used in explosive environment (Ex area). The unique dual sensor technology optimizes sensor sensitivity and accuracy by automatically selecting the ideal sensor type for the situation.
User-Friendly Output Signals

The S230/S231 come ready to use and simple to install with your choice of 4-20mA or Modbus RTU (RS485) outputs. If required, parameters can be quickly monitored through the service software. The transmitters can also be connected the Sigma 331 (stationary) or S551 (portable) data logger and the data can be transferred for further analysis..

Technical Data

MEASUREMENT
Dew Point
Accuracy: ± 1 °C Td (0 … 20 °C Td)
± 2 °C Td (-60 … 0 °C Td)
± 3 °C (-100 … -60 °C Td)
Selectable units: °C, °F, bar(g), MPa(g), psi(g), % rH,
g/m³, mg/m³, G/m³ atm., mg/m³ atm., ppm(v), g/kg, °C Td atm.
Measuring range: (model depending) S230: -100 … +20 °C Td
S231: -50 … +20 °C Td
Sensor: Polymer + QCM
Response time t90: (@ 4l/min) -20 °C Td -> -60 °C Td = < 240 s
-60 °C Td -> -20 °C Td = < 30 s
Temperature
Accuracy: 0.3 °C
Measuring range: -30 … +70 °C
Sensor: NTC
Reference conditions
Selectable conditions: Pressure Dew Point,
Atmospheric Dew Point
SIGNAL INTERFACE & SUPPLY
Analog output
Signal: 4 … 20 mA (isolated)
Modbus/RTU
Scaling: S230: 4 mA = -100 °C Td;
20 mA = +20 °C Td
S231: 4 mA = -50 °C Td;
20 mA = +20 °C Td
Load: 250R
Update rate: 3 / sec
Fieldbus
Protocol: Modbus/RTU
Update rate: 1/s
Supply:
Voltage supply: 15 … 30 VDC
Current consumption: 40 mA @ 24 VDC

GENERAL DATA
Configuration
PC Software: S4C-DP Application
Material
Process connection: Stainless steel 1.4301 (SUS 304)
Housing: Aluminium alloy
Sensor: Polymer, Ceramic
Miscellaneous
Electrical connection Screw terminals
Protection class IP67
Approvals II 2G Ex db ib IIC T4 Gb
II 2D Ex ib tb IIIC T135°C Db
CE
Process connection G 1/2“ thread (ISO 228/1)
Weight 728 g
Operating conditions
Medium: Air, Argon, O₂, N₂, CO₂*
Medium quality: ISO 8573-1: 4.6.3 or better
Medium temperature: -30 … +70 °C
Medium humidity: ≤ 20 °C Td
Operating pressure (model depending) -0.1 … 1.6 MPa (S230)
-0.1 … 35 MPa (S231)
Ambient temperature: 0 … +50 °C
Ambient humidity: 0 … 100 % rH
Storage temperature: -20 … +50 °C
Transport temperature: -30 … +70 ºC

Stated accuracy under following conditions:
Ambient temperature 23 °C ±3 °C
Process temperature 23 °C ±3 °C
Ambient humidity < 95 %, no condensation
Airflow > 2 l/min at sensor tip

Applications
Some common applications for compressed air dew point measurement in explosive areas include Chemical Processes, Hydrogen Cooling Systems, Spray Painting and Coating, Oil and Gas Drilling, Mining and Tunneling, Chemical Storage and Transport, Aerospace and Defense.