1. Quality
A. Noise
It refers to high frequency noise generated by linear pulses of electrical components, temperature fluctuation, voltage and other non-solubles; it also refers to irregular fluctuation of baseline.
Noise is directly related to detection sensitivity of the instrument, the larger the noise, the lower the detection sensitivity.
For measurement of low concentration gas samples, it requires the noise of instrument to be as small as possible. Otherwise, it will cause unstable baseline and even affect the analysis result.

B. Minimum detection concentration (Minimum detection limit)
It is an important parameter for sensitivity of instrument. Larger noise leads to larger minimum detection concentration, then, the sensitivity is low.

C. Drift
It refers to a distance which baseline drifts away from original point in a period of time after stabilizing of intrument. It is used for measuring the speed of stabilizing of instrument. High quality instrument will be stabilized in a very short time, then, it improves analyzing efficiency.

D. Repeatability
It is an important index for instrument stability. The stability of high quality instrument should be great. It requires the consistency of retention time and concentration of multiple injections. Then, its analysis result will be convincing.

E. Operation
Easier operation is good for improving efficiency of analysis.

F. Overall configuration
The instrument is an integrated system. You could not focus on single component and part. You shoud pay attention to all components and parts, and take all parts into consideration, including detectors, valves, columns etc.

2. Price
Is the price acceptable for you?

3. After-sales service and technical support
Transformer oil dissolved gas analysis is a very professional work, a good and continuous after-sales service and technical support will help you lot.