Hood steaming In the 1990s, the German company Seifert introduced an innovative surface steaming technology – large-surface steaming under steel or aluminium hoods. Compared with sheet steaming, this method has the advantage of a much higher steam transfer. Instead of 4kg per hour per square metre under the sheet, the hood allows for over 30kg per hour per square metre. The result is a significant reduction of the steaming time and also in heating oil consumption.
Energy consumption Depending on the steaming time and soil characteristics, you need 0.3 litres of heating oilper square metre to reach 8-10cm steaming depth, or 1 litre of oil to reach 25-30cm depth. You can achieve up to 85°C soil temperature with this method. With hood steaming, you therefore save up to 50% in heating oil compared with sheet steaming. Rules of thumb: 1. The longer the steaming time, the higher the energy losses and therefore the energy demand per square metre. 2. The steaming time for 10cm steaming depth is about 8 -12 minutes. 3. You can achieve 30kg steam per hour and square metre under a normal steaming hood*. Sandwich-type steaming is the only energy-saving method of surface steaming.
Know how! Tips and tricks Our special high-quality MSD steaming hoods are made of steel or aluminium. Their lifecycle is extremely long. They are used in greenhouses, tunnels and outdoors as they are very reliable. Depending on the desired steaming depth and soil properties, steaming hoods are moved in short intervals from 5 (for a steaming depth of 5cm) to 25 min (for a steaming depth of 20-25cm). If the application time is longer, you can also achieve temperatures exceeding 75°C even at 30cm depth to achieve sufficient soil sanitisation. Each MSD steaming hood is tailored to your individual requirements and manufactured to size. The hood dimensions will be sized on the basis of a steam transfer of 30 kg/hour/sq.m. In large-area greenhouses of sound and stable construction, you can hang hoods on runners and then lift and move them with pneumatic lift cylinders. Small and mid-size hoods can be very easily set manually with rocker lever systems or moved electrically with special cable pull winches. To adapt the hood to the greenhouse size, large steaming hoods can be supplied with a hydraulic adjustment unit so that their working width can vary on each side according to the user’s needs.
As soon as the steaming hood has started to move, we recommend covering the steamed surface. You can easily do this with a drag sheet, which can be simply fixed to the hood. The goal is to retain the residual steam in the soil and to let the heat act for as long as possible. The longer the heat can act, the better the sanitising effect will be. Automatic steaming hood in use: video on YouTube
Which steam boiler is the right one? The surface performance per cycle depends on the steaming depth, as well as on the size of the boiler and hood.
*Higher steam transfer rates exceeding 50kg/h/sq.m are possible if you use more materials and techniques (e.g. steel hoods, sandwich-type steaming, etc.) Depending on the soil properties and ambient temperature, the steaming time for one working cycle is about 8-10 minutes for 10cm steaming depth at about 80°C soil temperature.