Notes and recommendations for double membrane gas cylinders in winter

During the cold season, we would like to draw your attention to special care when operating your double diaphragm gas cylinder in winter weather conditions. To ensure trouble-free operation, system components that are particularly sensitive to weather conditions should be checked and maintained regularly.

To this end, we would like to provide you with the following information and recommendations:


To prevent the negative effects of heavy snowfall and extreme frost, it is advisable to keep an eye on the current weather forecast, especially in winter. If heavy snowfall and/or frost is forecast, precautionary measures can be taken and particularly sensitive parts of the system can be checked as a precaution.

▶ Check the support air pressure. Is the support air blower working properly?

▶ Are all exhaust air flaps free to move?

▶ Are the intake openings of the fans clear?

▶ Is there sufficient antifreeze in the overpressure/underpressure protection?

▶ Is it possible to install a snow clearing cable on the roof as a precaution?

▶ Can the gas storage tank be filled to use the heat from the stored gas?


▶ The roof of the double membrane gas storage tank must be checked regularly for snow.

▶ In the case of double diaphragm gas storage tanks, all fan intake grilles should be checked regularly in winter for frost formation and icing. In addition, exhaust air flaps should be checked for free movement. Icing can restrict the performance of the blowers and therefore the support air pressure recommended by us may not be maintained.

▶ If heavy snowfall is forecast, the support air pressure of the double diaphragm gas cylinder should be checked as a precaution. One mbar of pressure can carry 10 kg of snow load per m². If there is still a risk of the weather protection membrane being pushed in, countermeasures must be taken. In warm fermenters and secondary fermenters, the snow can be melted by filling the gas storage space. Depending on the moisture of the snow and the outside temperature, the snow can melt or slide off. In addition, tapping on the outside of the weather protection membrane can help the snow to slide off. Suitable tools for knocking off would be, for example, a broom with a telescopic handle or a 50 mm HT pipe. Caution: Do not use any sharp-edged tools.

▶ If the center of the weather protection membrane is dented by snow and/or water pockets, the gas storage membrane must be emptied in suitable weather conditions (no wind, no rain). The supporting air fan is then switched off. A rope or tensioning strap is thrown over the weather protection membrane and a channel is created by tying it in, through which the water can run off. Accumulations of snow can also be removed via this channel. Caution: Do not use any sharp-edged tools.


The vacuum/overpressure safety device should be checked for free movement at least once a day in winter temperatures – or several times a day in extremely cold weather (please refer to the maintenance and care schedule in the ÜUDS operating instructions).

▶ Please avoid blowing off biogas over a longer period of time (also for environmental reasons).

▶ Despite the use of very pure or very highly concentrated antifreeze in the pressure/vacuum relief device (recommendation down to -30°C), this can be diluted so much by internal condensation (condensation of water vapor on the cold surfaces) that the pressure/vacuum relief devices lose their frost protection. If an overpressure/underpressure safety device blows off for a longer period of time during frost, pipes and the technology can freeze due to the condensate freezing.

▶ In unheated “cold” fermentation product storage facilities, overpressure/underpressure safety devices are particularly susceptible to winter temperature conditions due to the lack of a heat source. They should therefore be checked before each frost period. The dilution effect due to condensate formation is less pronounced in fermentation residue stores than in relatively warm fermenters. If attention is paid to an exact fill level when filling the overpressure/underpressure safety device (see scale), it is immediately apparent if the fill level decreases due to evaporation or after blowing off. It is also immediately apparent if the fill level increases due to condensation.

▶ For safe operation, we strongly recommend the use of trace heating, especially for tanks with increased condensate formation and in areas with expected heavy and prolonged frost. We offer trace heating systems for overpressure/underpressure safety devices. For further information, please contact us on +49 (0) 8074 915 66-0

CAUTION: If the vacuum/overpressure safety device is frozen, please do not attempt to defrost it, e.g. with a hot air gun/gas burner. There is a risk of a biogas/air mixture igniting. A hazardous explosive atmosphere can occur at the chimney opening of the overpressure protection both in normal operation and in the event of faults. Non-explosion-proof devices may not be used there.

Defrosting with hot water is safer.


The mechanical level measuring device (especially draw-wire sensors) can freeze and therefore give unreliable values. Corresponding overpressure or underpressure can cause damage to the double diaphragm gas cylinder.

Depending on the weather conditions, these system components must be checked regularly for icing. Spraying the cord with silicone spray in the area of the deflection pulleys also prevents it from freezing.


With membranes screwed on with a flat profile, the slipping snow can accumulate on the top of the wall and lead to the membrane being pushed in sideways, unlike with clamp hose fastenings. For this reason, the top of the wall must be cleared if large amounts of snow have accumulated and any water pockets that have formed must be skimmed off.

Caution: Do not use any sharp-edged tools!

PRESSURE AIR CONNECTION SET for the clamping hose

Glykoler: As a preventative measure, approx. 0.6 liters of pure antifreeze should be flushed into the system annually before the frost period (for the procedure, see Glykoler operating instructions, page 7). Only the supplied antifreeze (ALGOREX radiator antifreeze -40°C) or agents with the same specifications may be used!

Screw and clamp connections should be checked regularly and retightened if necessary.


The use of thermal insulation film can reduce heat loss by up to approx. 30 % and thus save heating energy. Retrofitting is possible. For further information, please contact us on +49 (0) 8074 915 66-0


Depending on the shape of the roof and the size of the container, a rope can be thrown over the container. For roofs with a spherical cap shape and center flange, several cables can be attached to the center flange at the high point using eyebolts. The snow can slide off by pulling the cable sideways. Caution: Caution is required if a level sensor with the weather protection membrane is installed at the high point. After the snow has slid off, the supply air ducts and the exhaust air flaps must be checked for functionality.

For further information, please contact us on +49 (0) 8074 915 66-0


When working on and around the double diaphragm gas cylinder, please take care to protect yourself against accidents, in particular against slipping on frozen ground or slipping and falling on black ice. Make sure you wear gloves to protect against frostbite when touching metal parts. Always watch out for icicles or roof avalanches falling from roofs or the tops of containers.

If you have any questions or requests, please get in touch with us – we will be happy to help:
Phone no. +49 (0) 8074 915 66-0


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