Model 2750​​​

Portable Gas Analyzer​​​​

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 Description

The portable Model 2750 accurately and reliably measures hydrogen-in-CO2 and air-in-CO2 during maintenance purging of hydrogen-cooled turbine generators. These measurements assure that the purging proceeds quickly, efficiently and effectively. Switch-selectable ranges on the instrument make it easy to choose the measurement required. Plus, the 2750 features a third range that alerts the user to air leaks in the hydrogen cooling gas and thus helps assure optimum efficiency during normal generator operation.


Sensor Description

The sensor structure consists of an integrated heater located on a thin electrical and thermal insulating membrane. Two thin film resistors are used for heating and measuring the temperature of the membrane. Two resistors are integrated on the silicon beside the membrane for the compensation of the ambient temperature changes. Gases that have lower density than air (CH4) decrease on the surface membrane temperature. Gases with densities higher than ​air (CO2) increase the temperature of the measuring resistor.


Design

The 2750 is a rugged, portable, easy-to-use gas analyzer that monitors purge gases and the cooling gas in hydrogen-cooled turbine generators. Three selectable ranges monitor purge gas composition during maintenance purging and spot-checks hydrogen purity during normal generator operation. The portability of the unit eliminates installation costs and makes it easy to move between generators. There are no moving parts to wear out, no filters to change and no traps to clean; so, the 2750 is virtually maintenance free. A simple periodic calibration is all that is needed to assure years of trouble-free service.


Maintenance

To minimize downtime, it is important for the 2-step purge process to proceed quickly and effectively. The 2750 helps achieve those objectives. During the first stage of maintenance purging, the unit monitors the changing H2/CO2 mixture. This  allows operators to know the earliest moment to begin the second stage (air purge). This also saves money by minimizing CO2 usage. During the second stage, the 2750 monitors air-in-CO2, which helps you decide when workers can begin maintenance.


Other Benefits

  • Minimizes costly maintenance downtime

  • Saves money by avoiding needless waste of CO2 purge gas

  • Assures optimum efficiency by detecting air contamination



 Features

  • ​Three standard ranges:

    • 0-100% Air in CO2

    • 0-100% Hydrogen CO2

    • 80-100% Hydrogen in Air

  • Principle of operation: thermal conductivity

  • Temperature controlled thermal conductivity cell assures high accuracy and stability

  • Sealed reference cell

  • Area classification: General purpose (non-hazardous) areas

  • Electrical requirements: 110VAC, 50/60 Hz or 220 VAC, 50/60Hz

  • Signal output: 0-1 VDC

  • Integral digital meter

  • Integral flow meter

  • AC power cord

  • Instruction manual​


 Specifications

​Ranges

​0-100% H2 in CO2
0-100% Air in CO2
80-100% H2 in Air

​Accuracy

​± 5% of range at a constant temperature and pressure (once equilibrium has been achieved)
± 6% at constant pressure over operating temperature range

​Sensor Type

​Thermal Conductivity

​Resolution

​0.1% (gas) H2, Air and CO2

​Response Time

​0-90% in less than 10 seconds @ 0.5 SCFH

​Drift Rate

​Less than 1% (range)/day

​Display

​3-1/2 digit LCD

​Flow Rate

​0.1 - 2.5 SCFH normal
2.5 SCFH maximum
(0.5 - 30 PSIG)

​Wetted Parts

​Brass, SS, Aluminum, Glass, Teflon, Nylon

​Outputs

​0-1 VDC (0.8-1 VDC 80% to 100% range)

​Gas Connections

​1/8 tube and 3/16 barb

​Temperature

​32° to 104°F (0° to 40°C)

​Power

​9V DC power adapter powered from a 90-264 VAC 47-63 Hz VAC
(US type 2 prong plug)

​Enclosure

​NEMA-4X PET plastic housing

​Dimensions

​10.6"L x 4.8"H x 9.9"W (26.92 x 12.19 x 25.15 cm)
4.96 lbs (2.24 kg)


 Applications

Before workers can perform periodic maintenance inside a hydrogen-cooled turbine generator, the hydrogen (H2) cooling gas must be purged and replaced with a breathable atmosphere (air). However, air/H2 mixtures are potentially explosive, so a maintenance purge is used that proceeds in two stages. First, carbon dioxide CO2 is used to purge out the H2. Then in the second stage, air purges out the CO2.

 Downloads

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