GIEBEL Know How


QUESTIONS & ANSWERS

  

What pressure does an adsorber build up and why?

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Functionality Adsorber

All original GIEBEL Adsorbers® consist of harmless and reusable materials. This includes among others Acrylic glass, aluminium, galvanized steel, polyamide (PA), polyoxymethylene (POM), NBR, FKM, EPDM, activated carbon, silica gel orange.

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When is silica gel or activated carbon used in the adsorber?

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Whether the hydrophilic silica gel (water-attracting) or the hydrophobic adsorbent activated carbon (water-avoiding) is used depends on the objective of the application. If air humidity is to be prevented from entering the system, a silica gel filter is used. On the other hand, if the environment is to be protected from oil aerosols or other pollutants, an activated carbon filter must be used.

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Can an adsorber be mounted from top to bottom?

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An aeration dryer is always mounted vertically. The connection is located at the bottom of the system. This has advantages, because due to the constructional design the air inlet openings are on the same side and thus increase the IP protection. However, if an adsorber has to be mounted from top to bottom, this is possible up to a certain size. It is better to use the specially designed TB-RV series.

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Can silica gel adsorb liquid water?

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The question is often asked whether silica gel can absorb water? Yes, as long as it is present as humidity in the air or as the highest mist. Liquid water cannot be adsorbed by narrow-pored silica gel. Special silica gels or other adsorbents are used for this purpose. Liquid water produces such a high energy release that the silica gel grain is destroyed and breaks. This is visible in the adsorber as dust.

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Can silica gel be regenerated in the microwave?

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Silica gel is regenerable and can be reused very often - this is a major advantage of this desiccant and has contributed to its widespread use. But how is the silica gel dried in practical handling? Simple and effective is drying in a standard household oven at 120°C. But can silica gel also be regenerated in the microwave? Yes, but only under certain conditions.

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Is oil in a tank dried by an adsorber?

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If the oil in a hydraulic tank is already loaded with water, a ventilation dryer can help to a certain extent. On the one hand, no new moisture gets into the oil, on the other hand, the air inside the tank is dried and thus also the oil. However, this happens only very slowly and serves to solve the problem of oil drying.

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Why can an adsorber be loaded very quickly?

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If a ventilation dryer becomes saturated very quickly, this can have several causes. In this video we will deal with this. The most common reason is a high volume flow to be dried and an adsorber selected too small. On the other hand, it is possible that the moisture comes from the system and the adsorber is loaded from both sides.

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Combine nitrogen blanketing with adsorber?

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The use of a tank air dryer in combination with a blanket of an inert gas, such as nitrogen, is not necessary. The reason is the function of both approaches. The nitrogen blanketing creates a continuous overpressure. On the other hand, the adsorber needs a regular negative pressure to dry the sucked in air. This effect is explained in the following video.

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How many plugs must I pull out during assembly?

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When mounting an adsorber without valves, the openings are closed with protective plugs. In this way, the adsorber can be stored for a long time without loading. However, the plugs must be removed during commissioning. And there is always the question, how many? In systems with a slow air flow only 1-2 plugs, whereas in systems with a high air flow all 4 plugs.

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Do I use an adsorber with or without valves?

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We are often asked whether an adsorber should be used with or without valves. This decision depends on the plant and the application. It is important whether a long maintenance interval or a favourable purchase price has priority. Long maintenance intervals require the protection of the desiccant by valves.

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WHY DOES THE SILICA GEL IN THE ADSORBER TURN BROWNISH?

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In most cases silica gel orange-green is used when a breathing filter is used. In practice, the silica gel does not always turn green, but rather brown. We explain the reasons for this in our blog post.

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What is the maintenance interval of an adsorber?

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Anyone who uses an aeration dryer has already made the right decision. However, the interval until the next maintenance is individual. We explain the reasons for this in this article.

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What is the difference between KC Dry Beads OC and Silicagel?

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Silica gel, drying agent or silica gel? Different terms for the same substance? We explain the differences and their meaning for the use in an adsorber.

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How long can an adsorber be stored?

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If a ventilation dryer is not used immediately, it is important to store it correctly. What are the optimal conditions for the storage of an adsorber to maintain its full efficiency?

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What are the possibilities of regeneration/desorption?

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The terms adsorption and desorption are closely related to the topic of aeration drying. We explain the possibilities of regeneration and desorption in our current blog post.

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Is a hydrophobic PTFE membrane suitable for water separation?

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In our article, we explain why no membrane can be used for the separation of water droplets on hydraulic power units and the like. Adsorbers, however, are optimally equipped for this task.

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Which dew points are achieved with an adsorber?

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A ventilation dryer on hydraulic power packs, gearboxes, storage tanks, drums and IBC containers prevents the entry of water. When the right time for a replacement has come we will answer you in our current article.

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How can I check if my adsorber is working?

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Adsorbers are also used in plants that are not regularly operated. After a longer period of time, the question arises whether the aeration dryer still works. We will give you tips on how to check the functioning of the respiration dryer.

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What is the correct air flow rate for an adsorber?

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Which air flow rate or volume flow is correct for the successful use of an aeration dryer and how is it determined. In our current Question of the Month we pursue this question and give you the answer.

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How do I dispose of a used adsorber?

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Adsorber structure

All original GIEBEL Adsorbers® consist of harmless and reusable materials. This includes among others Acrylic glass, aluminium, galvanized steel, polyamide (PA), polyoxymethylene (POM), NBR, FKM, EPDM, activated carbon, silica gel orange.

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In which temperature range can an adsorber be used?

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When using an aeration dryer, the temperature is important because it has an influence on the mechanical components and, above all, on the physical process. The primary limiting component is the desiccant.

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How much water can an adsorber absorb?

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When using an aeration dryer, the temperature is important because it has an influence on the mechanical components and, above all, on the physical process. The primary limiting component is the desiccant.

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Why does the adsorber load from above?

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When using an adsorber on a hydraulic tank, gearbox, storage tank as well as drums and IBCs, the ambient air sucked in will flow into the adsorber from below (see figure).

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Can an adsorber be mounted horizontally?

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Basically, it is possible to install an adsorber in a horizontal position. However, a few factors must be taken into account during installation to ensure the function of the adsorber and to prevent damage to the system.

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What influence does oil have on silica gel?

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Silica gel is a very effective drying agent and stores polar substances in the pore structure. For this reason it is used in respiratory dryers on hydraulic tanks. In this video you can see what happens when oil mist from the unit gets onto the desiccant.

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Are there differences in the silica gels with color indicator?

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The aim of the experiment was to find out the differences between the usual silica gels when used in an adsorber. For this comparison, 0.5 kg each of the silica gels orange-green (OG), orange-colorless (OF), blue-pink (BR) and the KC dry beads OC (KC) were examined. The test conditions for all adsorbents were based on a mass flow of 46.6 g/h. This is calculated using a volume flow of 50 l/min, a temperature of 20 °C and a relative humidity of 90 %. All tests showed a behavior characteristic for silica gel. The breakthrough curves only differ at high loads due to the different maximum loads.

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What is the difference between molecular sieve and silica gel?

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The difference between silica gel orange-green and the molecular sieves 4A and 13X when used in an adsorber was shown in an experiment. For the experiment, 0.5 kg each of the desiccants were tested at a mass flow of 46.6 g/h. This is calculated using a volume flow of 50 l/min, a temperature of 20 °C and a relative humidity of 90 %. Due to the lack of a moisture indicator, key figures for the color changes are determined for the molecular sieves. The behavior of the breakthrough curves of the molecular sieves differs from that of the silica gel. The breakthrough curve of the molecular sieves rises steeply towards the maximum load up to the value 1. The steeper rise of the breakthrough curve indicates a more complete loading of the molecular sieves.

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Which color indicators are used in silica gels?

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Many silica gels are, on the part of the manufacturer, provided with a small amount of moisture indicators. They indicate a loading condition by a color change. The moisture indicators for silica gels are divided into two types:

  • pH-indicators
  • Metal salts

The pH-indicators function according to the principle of neutralization. In dry condition the indicator is surrounded by an acidic or alkaline environment. The environment is created by the indicator or an additionally applied acid or base. The entry of water sets the environment to a neutral pH value. This change of the pH-value leads to a color change of the humidity indicator.

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Can I regenerate silica gel in an oven?

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Prerequisite for the regeneration of loaded silica gel in a household oven is that there is no oil or other substances on the surface and that the regeneration temperature is maintained.

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Are silica gels with color indicators subject to labeling?

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The color indicator is important here. According to European Union legislation, pure silica gel, molecular sieve and alumina are not classified as hazardous. Furthermore, they are non-flammable and chemically stable. No ecological problems are to be expected when handled and used properly. If these adsorbents are used in aeration dryers, a silica gel with color indicator is often selected. Especially for silica gels, various color changes are available, which indicate a change from a certain water content on. Some color indicators are classified as toxic and hazardous to health. Such color indicators make the silica gels and thus also the aeration dryers subject to mandatory labeling.

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Can oil-loaded silica gel be regenerated?

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The negative influence of oil on silica gel is largely unknown, and there are no comparable experiments that provide relevant data on this issue. We did a preliminary test to gain a rough insight into this topic.

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