- Tank systems
- Air dehumidification
- Swimming pool technology
How safe are the buildings?
Initially, concrete walls certainly offer greater passive protection in comparison to wood or industrial hall walls. Using commonly available cordless drills however, a tank can be tampered with in a very short time, permitting direct access to the water. This isn't possible with HydroSystemTanks!
Intruders also generally don't go through walls, instead always entering via doors or windows as these are always the weakest links and allow intrusion with relatively little noise. This is why active object protection with door and window contacts and interior room monitoring with remote alarming is very important.
Tanks with HydroSystemTanks® are very easy to monitor thanks to being in clear view inside buildings.
However, it mustn't be forgotten that a water distribution system with a large number of building connections and publicly accessible hydrants is always an extremely vulnerable system in which the water storage tanks are generally regarded as one of the most secure components.
How long is the service life of wood outdoors?
With regard to surface composition, clear specifications can be found in DIN 18 334 (VOB Part C, Implementation provisions for carpentry and wood construction). Under Item 3.11, it is called exterior wall cladding: 3.11.1 Exterior wall cladding must be made of coarse, trimmed boards.
Wood is a fibrous material. When sawing lengthwise, individual fibres or fibre bundles (i.e. wood shavings) are torn out in the area of the cut due to the serration. This results in a correspondingly rough surface.
When planing, the cutting edge of the blade is led over the wood in the lengthwise direction of the fibre. This clips the fibres and opens them. Water or moisture can penetrate these open fibres more easily due to hygroscopic properties. This is why planed wood greys faster than rough sawn wood outdoors and provides fungal spores with ideal conditions for growth. In contrast, water beads up on rough sawn wood!
Woods with a high resin content, such as larch and Douglas fir, are especially suitable for surface cladding. Siberian larches are particularly weather-resistant. It has a high resin content, small branches and is characterised by denser growth.
When building with wood, it is also important to maintain a sufficiently great distance from the ground so that the wood can dry quickly after rainfall. Waterlogging (e.g. due to plant growth) must be avoided!
- Taking the building design aspects into consideration, a service life of 80 to 100 years can be estimated for the external cladding (as with mountain huts and farmhouses in the Alps).
How must floors be made in waterworks?
Floors in waterworks must always be such that they meet the requirements of the Workplace Ordinance.
Item 1.5 (1) says: The surfaces of the rooms' floors, walls and ceilings must be designed so that they meet the requirements for safe operation and can be cleaned both easily and safely.
And (2): The rooms' floors must not have any unevenness, holes, trip points or hazardous slopes. They must be secure to prevent sliding, stable, non-slip and anti-skid.
Requirements for floor coverings in work rooms and work areas with an increased risk of slipping are described in detail in the DGUV regulation 108-003. This regulation is limited to specifically to work rooms where, due to its usage, the floor comes into contact with slippery materials (the relevant work rooms are listed in detail in Appendix 1 of this regulation.).
It is also stated in detail 1.2 that this DGUV regulation does not apply to floors in work rooms etc. where conditions are dry and where there is no risk of slipping on slippery materials.
Nevertheless, in some tenders a certain level of antislip performance in line with assessment group R11 or 12 or even R13 is required for floor coverings in waterworks.
Such a requirement is contrary to the DGUV regulation 108-003, as it is firstly not justifiable and secondly the cleaning and care measures described under Point 5.1 have not been considered. Floor coverings with high antislip performance require intensive cleaning, which is normally only possible by using cleaning machines which suction removal of the cleaning liquid. Antislip coverings also greatly hinder water run-off. More details are described in the regulation.
Rough floor coverings with high antislip performance (greater than R9) in waterworks or drinking water tanks are
- required neither in accordance with the accident prevention regulations if the Workplace Ordinance
- not easy to clean
- therefore unhygienic
- and must therefore be avoided as a matter of urgency!
Is the water heated in hot summer weather?
Water has a comparatively very high specific heating capacity. In other words, Water is an excellent heat transfer medium. This is why it is also used to transport heat in heating systems. The amount of energy that can be transported with water is enormous. This means that the water tanks inside the building act as cool sinks in the summer and heat sinks in the winter. Thanks to very well insulated and wind-proof building shells, a constant room temperature is always maintained inside.
If the water would stop moving for months, temperature equalisation would slowly occur here as well. Water tanks are administered, however, and at least 50 to 70% of the water content is renewed daily. This means that temperature changes are, in effect, not detectable.
Moreover, considerably more heat is exchanged in the case of underground tanks where the tank walls contact the soil directly.
Does condensation form on the surfaces?
Condensation occurs when hot, humid air makes contact with cold surfaces to create so-called dew point undershoots.
The building's thermal insulation keeps the room temperature inside the building constant and approximately the same as the surface temperature of the stainless steel tanks. The humidity is also controlled by dehumidifiers. For this reason, condensation does not form on the tank surfaces during normal operation - neither on the inside nor on the outside.
- In summer in particular, the doors should also not be kept open for longer periods of time for maintenance work or inspections for example.
Can stainless steel corrode?
The corrosion resistance of stainless steel is attributable to the presence of chromium as an alloy component, the necessary proportion being at least 12%. Chromium forms an extremely thin but very resistant chromium oxide layer on the surface of the steel. This oxide layer protects the iron molecules against oxidation and makes the steel passive to a certain degree. This is why this layer is also referred to as the passive layer.
In simple terms, it can be said that the actual stainless steel has absolutely no direct contact with the medium, but is separated from the medium by a thin skin. Molybdenum also forms an oxide layer and thus also increases corrosion resistance.
Corrosion is essentially the process of metal removal. In aqueous solutions, corrosion is always attributable to basic electrochemical processes, with the metal serving as an electron conductor and the solution as an ionic conductor. A prerequisite for the presence of corrosion is therefore direct contact between the medium and the metal and a corresponding electrochemical potential. Otherwise, a corrosion process cannot take place. High salt content (chloride ions) can initiate corrosion on stainless steel. This is why hydrochloric acid may not be used to clean stainless steel surfaces.
Acid treatment is used in a targeted way to pickle a stainless steel component. The pickling agent is completely flushed off the component after the pickling process has been completed. The oxide layer then forms again on the surface with oxygen from the air.
Can nickel be released?
In order to solve the problem that gives rise to the question, it is necessary to deal to some degree with materials science, especially the question of how nickel affects stainless steel. Non-rusting austenitic chrome-nickel steels (V2A and V4A) have a chrome content of at least 18% and a nickel content of 8 to 10%.
Austenite designates a special crystallization form of the mixed crystals, which in unalloyed steels occurs only at temperatures above 906 °C. As an "austenite creator," nickel is the most important alloy element of austenitic stainless steels and enables this form even at room temperature, which is recognisable by the fact that these steels cannot be magnetised.
Duplex steel has a chromium content of at least 21 to 23% with a reduced nickel content of only around 1.5 to 2.5%. Due to the reduced nickel content, only about 50% austenitic structure is achieved, whereas the remainder is ferritic structure. Duplex steel is thus a mixed-structure steel.
With all of these steels, the alloy element nickel is permanently incorporated into the crystal structure and is not applied to the surface, as is the case with nickel-plating, for example.
The mobilisation of nickel from stainless steel cannot occur in normal operation, as the passive layer essentially acts as an insulator which would first have to be overcome.
Drinking water always contains a certain quantity of ions of many different materials and is therefore also an electrical conductor. However, normal drinking water is unable to have a corrosive effect on the stainless steel. Surface-related mass loss rates are, for all practical purposes, not measurable. For this reason, nickel cannot be released either.
Non-corroding stainless steel can be used in without any problem to supply drinking water. It is inert and hygienic. This is why stainless steel is also used almost exclusively in the foodstuffs industry, for example in the storage of mineral water.
If the limit value is overshot with nickel in the drinking water, this can generally be traced back to insufficient water composition in a corrosive interaction with nickel-plated fittings and a long service life. Any influence by stainless steel tanks can be definitively ruled out, however.
This hypothetical consideration shows that, for example, an increase in the nickel content in drinking water by 0.001mg/l (corresponding to 5% of the limit value of 0.020 mg/l) with a storage content 1,000 m³ would require a material removal of 1 g/day. With a 10% proportion by weight, this would mean a loss of 10 g of stainless steel per day. It goes without saying that this certainly cannot be the case.
Moreover, nickel allergy is a contact allergy (nickel-plated jewellery on skin) – oral intake has no effect here.
Why does room air dehumidification require too much electricity?
The dehumidification of air is a complex subject. Several reasons are therefore basically conceivable.
Examine the following when looking for the cause:
- Is the room to be dehumidified sealed off air-tight to the external atmosphere? If moist external air is constantly fed in (e.g. window open), run times are drastically increased!
- Is the unit properly set, e.g. to operation with an external sensor and not to continuous operation? Is the switching function correct?
Note: If the cable is incorrectly connected on the sensor's changeover contact, the dehumidifier can run in continuous operation, even though the sensor is not been activated.
- Is the hygrostat or the dew point sensor properly set and, above all, located in the right place
Note: Operation with a dew point sensor is normally the most effective dehumidification method. The dehumidifier is not activated until the sensor indicates that the condensation point has not been reached. The condensation point sensor (only one makes sense) installed on the pipeline with the lowest temperature (normally the inflow) controls the dehumidifier(s). If there are several dehumidifiers, the switching commands for them should be managed via a control unit. Two sensors in parallel can never be set so that the switching operations occur synchronously.
- Are the dehumidification capacity and the required circulation capacity adapted to the room volume to be dehumidified, and is the dehumidifier set up in the correct place?
Additionally with condensation dryers:
- Does the condenser get sufficiently cold when in operation? If not, there is either insufficient coolant in the circuit or the unit is faulty, and continuous running can be the result.
- Type HD 370: Bends or air duct tubes are not absolutely essential with this type. Very good air circulation is achieved thanks to the great pressing of the ventilators.When the dehumidifier is operated without pipes/bends, the baffle plates that are normally supplied with it must be installed. Otherwise, without baffle plates, it is possible for the energy of the circulated air to be greater than the energy that the cooling unit dissipates. In consequence, the condenser does not cool down sufficiently and there is no or only very insufficient condensation. Although the unit still works, it does not dehumidify or does not do so properly and this becomes apparent from the increased run time.
With adsorption dryers with outside air feeding:
- These units work well with cold dry outside air. With warm moist outside air however, the situation can arise in which the moisture from outside is transported into the building. In this case, the units must be switched off and condensation dryers must be used.
Air dehumidification in waterworks helps to preserve the long-term value of the often high-value systems and building structures. This enables the formation of condensation on surfaces and in walls to be permanently prevented. When operated properly, the benefits are significantly greater than the costs.
More information can be found in the document climate management in water technology systems.
When and why was the ozone-bromine method developed?
Up until 1974/1975 there was no simple chlorine-free water treatment method for private baths. Dosing with bromine was very complex, prone to failure and not without hazards. The process development made ozone water treatment available for private baths also. The combination of ozone and bromide salt proved to be a very efficient, reliable and very easy to use method.