MAS-100 CG® Ex

Electronic components tolerance and the resulting effects to sampling precision:

Principal, the global timing of the microcontroller PCF80C552, implemented in the MAS100CG Ex is generated by a quartz with a fundamental resonance frequency of 11.0592MHz and a temperature coefficient of 50ppm/C (0.0050%/C). This device is connected to a feedback-amplifier in the microcontroller and to 2x 27pF - ballast capacitors with intrinsic production tolerances of +-5%. In conjunction with the quartz reference of 11.0592MHz, this capacitive tolerance generates a deviation of approx. 0.02% by slightly pulling the quartz resonance out of the fundamental frequency. Considerations to the thermal deviation of this components can be nearly ignored for operating ambient temperatures between 0..50C; the resulting tolerance of the
resonance frequency will be approx. 0.25%.
A more essential consideration is the interrupt latency time of the microcontroller of approx. 20us +-10us to enter the timer interrupt routine of 100Hz (10ms) for all timing functions as consequence for the sampled volume resp. gas mass. Because the interrupt latency time is a statistical function, the deviation of the sampled volume may be relatively large for a 10ms timepiece (+- 0.1%) of the massflow/volume
regulator, but due to the nature of the statistical interrupt latency time, this deviation will be compensated in less than 1s (within max. 100 timer interrupts) of a running sampling.

The total amount of frequency shift and as consequence the sampling precision deviation will be calculated as following:
- capacitors, pulling the quartz out of fundamental resonance: 0.02%
- temperature coefficients of quartz and capacitors 0..50C: 0.25%

Total sampling tolerance due to component tolerance: 0.27% max.

Those and all other tolerances (mass flow and pressure sensors) are always compensated by calibration.

Why to use a special instrument for compressed gas?

The MAS-100CG Ex is especially designed to work with pressures up to 10 bar. It is connected directly to the compressed gas pipes.

Which compressed gases might be used with the MAS-100 CG® Ex?

The MAS-100 CG® Ex is calibrated for compressed air, nitrogen, argon, carbon dioxide. Other gases might be used but must be calibrated.

What type of metal is the sampling head made of?

The sampling head is made of anodized aluminum. It is pressure tested up to 20 bar. Both parts have a serial number which are for the pressure test.

Why is the MAS-100CG Ex explosion proofed?

The gas distribution systems in companies might be in explosion risk areas. For security reasons the MAS-100CG Ex fits the standards for explosion proofed areas.

Is it possible to sterilize head and tubing?

Both head and tubing are sterilizable, 20 minutes at 121.

What is the principle behind the MAS-100 CG® Ex?

The MAS-100 CG® Ex works with a mass and a pressure sensor. Both sensors will regulate a valve in order to get constant flow of 100litres/minute over the range of 0.5 - 10 bar.

What is the MAS-100CG Software for?

The MAS-100 CG Software will handle data between MAS-100CG and PC. 10 Protocols with 10 sampling positions may be down/uploaded from MAS-100CG. Data collected are: time of test, place, user, and the volume as well as a report of errors.

What type of Petri dish may I use?

Ask your local supplier for 90-100 mm Standard Petri dishes with TSA-Agar (or equivalent for total count) which are double or triple packed and are sterilized by radiation.