SERVOPRO DF high purity

The DF-740 measures trace moisture in ammonia gas for LED plants

A trace moisture analyzer using Tunable Diode Laser (TDL) sensing technology, the DF-740 is designed to measure contaminants in UHP-grade ammonia.

Trace moisture measurements for quality control of ammonia gas production in LED plants

The DF-740 is designed specifically to monitor trace levels of moisture in electronics-grade ammonia (NH3) used in LED plants. Industry-leading TDL sensing technology and a robust Herriott Cell enable an exceptionally broad measurement range of 10ppb-10ppm.

By ensuring moisture only comes into contact with minimal optical components, the DF-740’s performance is unaffected by loss in mirror reflectivity – ensuring a fast response measurement that is stable, accurate and consistent.

The DF-740 is designed for long-term unattended operation, delivering considerable cost-savings. The high-stability optical TDL technology requires minimal ongoing maintenance, with zero drift enabling greatly extended calibration intervals.

Mike Proctor
Mike Proctor
Business Unit Director, P&S

High stability TDL measurements

When you need a solution that can undertake quality checks of electrograde NH3 during bulk gas checks for LED manufacture, you need a device that delivers high measurement accuracy, excellent stability – and is capable of being left unattended for extended periods. A robust design that removes issues associated with mirror reflectivity loss is a must and so is the need for a broad monitoring range. No matter your specific application needs, you’ll want a moisture analyzer that can reduce your ongoing costs and provide operational efficiencies. We don’t believe you should have to compromise.

A no compromise solution

The DF-740 has been designed to deliver optimum performance in the measurement of trace moisture in ammonia. This device uses leading-edge TDL sensing technology housed in a sturdy Herriot Cell, ensuring there is no loss of mirror reflectivity, thanks to minimized moisture contact with any optical components. This ensures the DF-740 gives a measurement that is highly stable, reliable and capable for being left unattended for long periods – a benefit supported by comprehensive data logging which captures and recalls calibration, system error and measurement data.

Simple maintenance and reduced ongoing costs

The DF-740 is also optimized to provide significant cost savings over a long product lifetime. The use of a high stability, zero drift TDL sensor extends calibration intervals and minimizes ongoing maintenance. In summary, the DF-740 is the ideal solution for your gas monitoring needs, thanks to the combination of its ultra-high performance capability, stable reliability and operational efficiency potential.

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The benefits of TDL moisture measurement

The high-performance DF-740 analyzer offers ultra-stable monitoring and significant cost savings.

Extended maintenance periods

Ultra-stable TDL sensing means that the DF-740 requires less frequent maintenance, while requirements are simple, with no consumables required.

High reliability

By minimizing water contact with optical components, the DF-740’s repeatable baseline measurements are unaffected by loss in mirror reflectivity, ensuring accuracy and stability.

Exceptional performance

The DF-740’s analysis is immune from gas cell concentration, ensuring the analyzer continues to operate to specification with up to 90% signal loss.

Unrivalled performance

  • Analysis immune from gas cell concentration: DF-740 operates to specification with up to 90% signal loss
  • 10ppb Lower Detection Limit (LDL)
  • Manufactured by Servomex – over 70 years’ experience innovating gas analysis with thousands of units used in the field


  • Trace level Tunable Diode Laser (TDL) sensing provides high stability measurements through minimal moisture contact with optical elements
  • Broad detection range: 0ppb – 10ppm
  • Operable via front panel or digital communication options

Easy to use

  • Simplified ongoing maintenance requirements with no consumables required
  • High reliability; repeatable baseline measurements are not affected by a loss in mirror reflectivity
  • Designed for long term unattended operation with minimal maintenance needs

Low cost of ownership

  • Maintenance periods extended by the use of patented ultra-stable, TDL sensing technology
  • Zero drift reduces calibration requirements

Benchmark compliance

  • IEC 61010-1
  • Overvoltage Category II, Pollution Degree 2
  • EU EMC Directive
  • EU Low Voltage Directive

Gases sensed, measurements and technologies

The DF-740 uses TDL sensing technology and a robust Herriot Cell to deliver trace moisture measurements in a broad range.

Gas Measurement
Water vapour (Moisture) (H₂O)ppm, ppb


Tunable Diode Laser


  • IEC 61010-1
  • Overvoltage Category II, Pollution Degree 2
  • EU EMC Directive
  • EU Low Voltage Directive

Schematics (select to expand)


483mm (19”) Wide x 266mm (10.5”) High x 608mm (23.9”) Deep


31.8kg (70lbs)

Get the detailed specifications

“For in-depth specifications you’ll want to download our technical datasheet which includes information on technology, performance, operating environment, sample conditions and compliance along with technical drawings and top-level benefits and applications.”

Mike Proctor
Mike Proctor
Business Unit Director, P&S

A single download with all the information you need

“Our resource pack for the DF-740 contains full details about the features and advantages of this trace moisture analyzer. Download it now to learn more.”

Mike Proctor
Mike Proctor
Business Unit Director, P&S

Manuals and brochures

Discover the DF-740’s benefits and technical specifications – download the product brochure and operator manual today.

SERVOPRO DF-740 NanoTrace Installation and Operator Manual

SERVOPRO DF-740 NanoTrace Installation and Operator Manual

SERVOPRO DF-740 Product brochure

SERVOPRO DF-740 Product brochure

DF-700 Gen 6 Series Recommended Spares

DF-700 Gen 6 Series Recommended Spares

Typical applications

A combination of high performance, ultra-stable measurements and affordability makes the DF-740 an attractive solution for electronics-grade NH3 quality checking applications.

Trace NHanalysis for quality control of electronics-grade bulk gases used in LED production | Trace NH3 analysis for leak detection of electronics-grade bulk gases used in LED production

UHP Gases / Semiconductors

A comprehensive systems solution

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