The scrapers serve to protect the interior of the hydraulic system, preventing the entry of contaminants into its cylinders. The cylinders that make up the hydraulic group need to operate in optimum conditions. The entry of contaminants, whether in greater or lesser volume, can have a great impact on the performance of the cylinders, and can cause part of the system to become unusable, which would entail a costly repair.
In today's article, we will focus on the most critical hydraulic systems, The pressure to which it is subjected, the temperature conditions of the application or the high presence of contaminants.
For example; this is the case of the backhoe, a hydraulic system that is subjected to high pressure, oscillating temperatures (the variation between day and night temperature is strong) and a dirty environment.
Index
Critical factors in hydraulic system scrapers
Particulate pollutants
One of the most dangerous points in a hydraulic system is the entry of contaminants into the cylinder. The cylinder has to work in an environment full of solid particles such as sand, rock, dust and many others, which can come into contact with water, and also has to cope with the weather conditions of the environment. The scraper is often one of the least expensive elements of the machine assembly. For this reason, it is necessary to select it on the basis of criteria that guarantee its correct operation, which will prolong its useful life.
The wiper to be used in extreme hydraulic systems must have a robust design and a mounting that allows strong interference fit between its lip and the cylinder rod. This point is vital to prevent the entry of any of the above-mentioned particles. In addition, it must have a high wear resistance by abrasion, caused by friction with all kinds of particles plus the temperature factor.
Pressure, temperature and extreme environments
The scraper shall withstand the high pressures of heavy hydraulics, The strength and material of the seal will therefore again be decisive.
Polyurethane is a good choice, The new, high pressure, high temperature, high mechanical resistance, can work in environments with temperatures ranging from -40ºC to 90ºC, and in high pressure applications.
However, it has the problem of hydrolysis. This phenomenon occurs when polyurethane is in contact with water or in humid environments. Therefore, it is necessary to select a special polyurethane, formulated to resist this phenomenon.
Contact with critical media
Nowadays, there are many applications where the scraper has to work in contact with critical media, e.g. in the chemical industry.
This is the case with the industrial mixer in a chemical processing plant, which is dedicated to the compaction of any type of product. In this case, the selection of the scraper will be oriented to the contact with the substance to be processed and also to high temperatures, due to the washing that this type of machinery requires to be able to produce in a clean and bacteria-free way.
In such a system, factors such as pressure will take a back seat, but the environment and temperature are of great importance.
A good choice could be the PTFE scrapers, This prevents the chemical attack from impairing the proper functioning of the system.
In addition, this type of machine is usually washed with the CIP system, which consists of circulating a mixture of hot water and dissolved chemical products through the equipment. For this reason, the PTFE-based scraper is essential to withstand both the washing temperature and the action of the chemical components of the mixture.
For more information, do not hesitate to consult our team of experts, who will propose the best solution for your application.
