The TLS "MonoGaso"

Uses of these instruments

MonoGaso

A very simple, low cost, yet accurate gas respirometer

MonoGaso

MANUAL OR DIGITAL

This device definitely belongs in the low technology "KISS" catagory. It was developed as a low cost (starting at $348 for the basic instrument as pictured) method of yeast respiration evaluation for yeast manufacturers and the baking industry. As gas is generated in the reaction vessel (which is placed in a temperature controlled water bath) it displaces water from the reservior into the large bore manometer tube. Since the relative increase in pressure is minimal, the volume of gas generated is read as Gasograph Units on the manometer tube. A calibration curve is available for each unit, when ordered, that enables the user to convert GU into cubic centimeters of gas generated if required. An electronic digital interface is an optional accessory. This accessory reads out in tenths of a GU enabling more precise reading of the manometer and thereby eliminating human interpolation errors. A proportional 0 to 5 volt output signal from the interface provides low noise data collection and reduction by computer or stripchart recorder. Gas capacity of the basic instrument pictured is 246 cc stp. The MonoGaso is based on the original Demaray Scientific Instrument, Ltd. "Gasograph" which has been proven by more than 20 years of respected use by yeast manufacturers and the baking product development divisions of large food companies. Photo of original Gasograph

For the more scientific individuals who are in need of reference to a refereed publication, we refer you to the original scientific paper on the "Gasograph" that was published in Cereal Chemistry, Vol. 57, No. 3, pp 212-216. (Web Search on "Gasograph"). Many of these instruments are still in use more than 14 years since they were last produced.

Click on the following links for information on operating procedures, and technical specifications. For prices please contact Three Links

Digital MonoGaso

The automated digital readout/data acquisition system is comprised of a "T' in the reaction vessel/reservoir tube which then leads to a sensitive pressure transducer plus a stainless steel stand for the readout. A 4 1/2 digit panel meter displays the manometer level in GU and the output from the transducer is amplified and conditioned to provide 0 to 5 volts for a standard strip chart recorder input or input to a DAQ card in your PC.

TLS is now providing complete data acquisition hardware and software for this option.

The above illustrated Wheaton glass jar and rubber stopper reaction vessel is inexpensive but we recommend that it be replaced with the more convenient stainless/PVC reaction vessel if the customer has no interest in simultanious proof height estimations. There are a number of advantages to replacing the jar with the more elegant stainless/PVC vessel. The 200 cc larger volume makes for potentially larger sample sizes. It will not break if dropped. The lids of both the glass and the stainless reaction vessels are equipped with O-ringed quick disconnects that have minimal volume displacement upon connection. This allows venting of the initial thermal expansion as the vessel is placed in the water bath prior to attaching the gas hose to the manometer. This improves accuracy and repeatability. This quick disconnect O-ringed Delrin fitting also makes separating the lid and gas hose for washing quick and easy while maintaining leak tightness over repeated disconnects. PVC coated lead weights are available from TLS that are designed to keep the stainless vessel submerged completely in the water bath to assure uniform temperature from test to test.

The non-linearity of volume response is ~3.1% at 100 GU due to the increasing head. For comparative measurements this is of no consequence what-so-ever. Its repeatability will be in the +/- .1% range. This is assuming of course that the thermal environment is constant. In a drafty lab or for long fermentations it is recommended that the MonoGaso be placed in the same water bath as the reaction vessel.

The instrument may also be used in reverse to measure gas consumed in a reaction or biological process. Pump it up to 100 GU with the gas of interest and observe consumption in GU over time. This assumes, of course, that water vapor is of no consequence in your reaction.