SERVOPRO DF high purity

The TDL DF-745 measures moisture for UHP gas checks

Using industry-leading Tunable Diode Laser (TDL) technology, the DF-745 delivers trace and ultra-trace measurements of moisture for ultra-high-purity (UHP) electronic gas checks in LED/LCD manufacturing processes.

Trace/ultra-trace moisture measurement of UHP gases

The DF-745 provides trace and ultra-trace moisture contaminant measurements for LED/LCD manufacturing processes. Able to monitor multiple background gases, it delivers exceptional performance operational flexibility in a compact unit.

With an intelligent and robust hardware/software design, this analyzer can be moved easily from port to port, virtually eliminating dry down times often associated with these applications.

Offering a Lower Detection Limit (LDL) of 1 part-per-billion (ppb), the DF-745 delivers ultra-reliable baseline measurements and a fast speed of response. A robust Herriott cell prevents loss in mirror reflectivity, while moisture contact with optical components is minimized, ensuring an accurate measurement. Zero drift extends calibration intervals while minimal ongoing maintenance provides a low cost of lifetime ownership.

Mike Proctor
Mike leads our expert Purity & Specialty team in providing products, knowledge, and service to the industrial, medical, UHP, and semiconductor gas markets. Mike Proctor
Business Unit Director, P&S

Flexible TDL trace and ultra-trace measurements

Modern LCD and LED manufacturing processes require an
ultra-trace quality measurement for moisture contaminants in high purity electronics grade gases. In such a specific application, users need analysis capable of delivering high-accuracy and ultra-low detection limits in multiple background gases. No matter how specific the application requirement, you’ll want a device that actively reduces ongoing costs to deliver a long and cost-effective lifetime of ownership. We don’t believe you should have to compromise.

A no-compromise solution

Utilizing advanced Servomex Tunable Diode Laser (TDL) sensing technology, housed in a robust Herriot cell, the DF-745 delivers a fast, accurate trace moisture measurement with a low detection limit of 1ppb. The measurement stability of TDL means the DF-745 exhibits zero drift and recovers fast from upset prone applications. Application flexibility is optimized through a compact size that keeps port to port mobility simple.

Simple maintenance and reduced ongoing costs

Proven sensing technology and advanced functionality delivers DF-745 users a low lifetime cost-of-ownership. Factory pre-calibration helps facilitate quick and easy installation; the use of the high stability, TDL sensor – with zero drift potential – extends calibration intervals and minimizes ongoing maintenance needs, enabling considerable savings over a long product lifetime.

Man with Servomex System components

Get the benefits of our systems expertise

If you need a gas analysis system, contact our expert team. We can manage your project from start to finish, with the knowledge and engineering skills to ensure you get a system that matches your exact requirements.

Ready to buy? Here’s how it works

It’s easy to find the product you need for your application with Servomex

Servomex UK technical center


Get in touch to tell us what you need and the application you plan to use it for

Servomex Gas System Schematics


Our expert team will help you select the right product package, ensuring you have the accessories and support to get the best performance from your analyzer

Woman Assembling Sensors


Your analyzer will be assembled in one of our state-of-the-art engineering centers and rapidly dispatched to your site

The benefits of TDL moisture measurement

The high-performance DF-745 analyzer offers ultra-stable monitoring and significant cost savings.

Exceptional performance

The DF-745’s analysis is immune from gas cell concentration, ensuring the analyzer continues to operate to specification with up to 90% signal loss.

Extended maintenance periods

Ultra-stable TDL sensing means that the DF-745 requires less frequent maintenance, while requirements are simple, with no consumables required.

High reliability

The DF-745 minimizes water contact with optical components, so its repeatable baseline measurements are unaffected by loss in mirror reflectivity, ensuring accuracy and stability.

Unrivalled performance

  • Uses industry-leading, high stability TDL sensing technology
  • Analysis immune from gas cell concentration: DF-745 operates to specification with up to 90% signal loss
  • LDL reference 1ppb
  • Manufactured by Servomex – over 70 years’ experience innovating and pioneering gas analysis and thousands of units used in the field every year


  • Trace level Tunable Diode Laser (TDL) sensing provides high stability measurements
  • Broad detection range: 0ppb – 20ppm
  • 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
  • Compact with a low weight; moves easily from port to port and ideal for other mobile applications

Low cost of ownership

  • Maintenance periods can be 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

With TDL sensing technology and a robust Herriot Cell, the DF-745 deliver trace and ultra-trace moisture measurements with a Lower Detection Limit of 1ppb.

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)


19 inch (48.3cm) Wide x 10.5 inch (26.7cm) High x 22.5 inch (57.2cm) 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

Download the resource pack for the DF-745

“We’ve collected all the information you’ll need about the DF-745 into a single download. Get it now to discover all the features, benefits and technical specifications of this trace and ultra-trace moisture analyzer.”

Mike Proctor
Mike Proctor
Business Unit Director, P&S

Manuals and brochures

Download the product brochure and operators manual to learn more about the performance of the DF-745.

SERVOPRO DF-745 Product brochure

SERVOPRO DF-745 Product brochure

DF-700 Gen 6 Series Recommended Spares

DF-700 Gen 6 Series Recommended Spares

Typical applications

The DF-745 is specifically designed for trace and ultra-trace moisture contaminant measurements in LED/LCD manufacturing processes.

Bulk gas quality control checks for ultra high purity electrograde gas production in LED plant applications | Leak detection in LED and LCD plant applications 

UHP Gases / Semiconductors

A comprehensive systems solution

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