Clean oil for productive machines - STAUFF Desiccant Breather in the fluid magazine

10 fluid · 06 2022 Spektrum principle is always the same: An initial filter layer sepa- rates out the solid particles. The pre-cleaned air flows through a capsule with desiccant before it is then “fine” filtered and discharged into the hydraulic reservoir. The different series in the Stauff desiccant air breather range all have the same water absorption capacity. The flagship among desiccant air breathers The key feature of the particularly robust and sturdy SDB series is a central stainless steel tube. It is positioned in the centre of the assembly and allows the breather to be used even in the most adverse conditions, for exam- ple strong vibrations. This central tube is surrounded by a transparent housing made of UV-resistant polycarbon- Part of it for 20 years – desiccant air breathers in the Stauff portfolio Desiccant air breathers are not new in the Stauff portfolio. They have been a part of the hydraulic accesso- ries range from the outset, when it was launched in 1999. Ralf Hart- mann has been with the company almost as long. He is a develop- ment engineer for hydraulic acces- sories at Stauff Germany in Wer- dohl. Mr Hartmann, what role do desic- cant air breathers play in the Stauff portfolio? Ralf Hartmann: The desiccant air breathers were initially more of a secondary product when the hy- draulic accessories range was laun- ched in 1999. We have recently seen the demand for desiccant air brea- thers increase, which prompted us to expand our range in this area. On our blog, we have dedicated an in- formative 21-part video series to this topic. We are recognising the key role of dehumidification when it comes to the safety and stable availability of hydraulic system. Why are “simple” breathers for hy- draulic reservoirs no longer enough for the manufacturers of hydraulic machines? One reason is the complexity of the machines. The moisture tolerance is lower, which has made manufactur- ers and users more sensitive to this issue. Some of the components have become more sensitive as well. In addition, people expect a high level of reliability from their machines. They want to extend the mainte- nance cycles and minimise down- time due to malfunctions or repairs. Contamination and premature ageing of the hydraulic oil caused by moisture are the most frequent triggers for machine failure. As the ventilation of the hydraulic tank is the main point of ingress for moist air, it makes sense to equip them with desiccant air breathers. The desiccant mate- rial consists of 25 % silica gel and 75 % molecular sieve. Image: Stauff ate which contains the desiccant, embedded between two filter discs: 25 % silica gel and 75 % molecular sieve. The stainless steel tube not only absorbs vibrations or impact from stones or similar objects. It is also embedded at the centre of the assembly in such a way that no desiccant could get into the hydraulic reservoir even if the housing was damaged. The flagship in the Stauff range can be equipped with check valves. They separate the desiccant from the ambi- ent air while no air flows in or out. So when the system is idle, no humidity is absorbed from the air, increasing the service life of the desiccant. Where can such extreme conditions be expec- ted? In large stone crushing systems, in the mining industry or other areas of mobile hydraulics where large gear-boxes and engines generate strong vibrations. But the SDB series is also used where maintenance intervals have to be re- duced significantly, for example in wind turbines. The compact all-rounder The compact SDBL series was developed for stationary systems and construction or agricultural machines that are used in complex, but less extreme conditions. An inner stainless steel tube is not required here. The plastic housing is impact resistant and shock resistant and has a female BSP thread. The series offers many features that are also available on the high-end SDB models, such as easy replacement of the desiccant or optional use of check valves. The crucial different compared to the robust version is, however: The SDBL series has a female thread and the air filter element is not positioned on, but within the assembly. This makes these breathers shorter and allows them to be used even if there is only little space available above the oil reservoir. Users can easily screw on addi- tional accessories, such as an oil mist separator, without changing the height of the system. The female thread offers many adaptation options, which is we call it an “all-rounder”. A simple version is sufficient if the strain on the unit is low. The third series – SVDB – is the simplest design: It has a solid plastic housing similar to the SDBL models.