1 Scope
This document specifies a method and procedure for extracting a liquid sample from a hydraulic system in operation. This document applies to the extraction of fluid samples for particle contamination analysis in hydraulic systems.
2 Normative references
The contents of the following documents constitute essential provisions of this document by means of normative references in the text. Among them, the date of the reference documents, only the date of the corresponding version applicable to this document; do not note the date of the reference documents, the latest version (including all the revision of the list) applicable to this document.
GB/T 14039 Hydraulic drives - Fluid solid particle contamination class codes (GB/T 14039-2002, ISO 4406, 1999, MOD)
3 Terms and definitions
GB/T17446 defined as well as the following terms and definitions apply to this document.
3.1
Clean sample botfleclean sample botfle
A clean bottle that has been cleaned and tested in accordance with GB/T 17484.
3.2
Line fluid sampling
A fluid sample is taken from the turbulent section of the hydraulic line fluid flow.
3.3
Tank reservoir fluid sampling
A sample is taken from the tank of a hydraulic system in operation.
3.4
Sampler sampler
A device that extracts a representative amount of fluid from a hydraulic system.
4 Setting of sampling points
4.1 General rules
4.1.1 The location and number of sampling points should be appropriate to the cleanliness requirements of the hydraulic system and the purpose of the sampling analysis.
4.1.2 The sampling point should be located on the main flow line of the monitored object as far as possible.
4.1.3 Sampling points should be located in areas that are easily accessible for on-line analysis or for sampling with clean sampling bottles.
4.2 Typical locations
4.2.1 Upstream of the main return line filter. This is the best location to diagnose the operating condition of the hydraulic system as the fluid sample at this location will indicate the level of contamination.
4.2.2 Downstream of the main pressure line filter. The fluid sample at this location will indicate the level of contamination entering the hydraulic system actuator.
4.2.3 Upstream of the hydraulic pump housing drain line filter. The fluid sample at this location indicates the level of contamination of the hydraulic pump.
Note. Due to the presence of particles generated by the wear of the hydraulic pump, the hydraulic system housing drain is probably the most contaminated part of the hydraulic system.
4.2,4 Downstream of the main return line filter or upstream of the hydraulic pump. The fluid sample at this location can characterise the performance of the return filter and also indicate the level of fluid contamination entering the tank and hydraulic pump.
Note 1: In some hydraulic systems, contaminants from the hydraulic system's case drain line and from outside air may have a significant impact on the level of contamination in the tank.
Note 2: For hydraulic systems with a bypass recirculation filtration system, the bypass recirculation filtration system (19) may affect the level of contamination of fluid samples taken upstream from the hydraulic system.
4.2.5 Samples from tanks and filter housings should not be taken for contamination analysis except in special circumstances.
Note: Fluid samples from this location may not fully characterise the operating conditions of the hydraulic system and may not be representative of the level of contamination of the fluid in the hydraulic system.
5 Selection of sampling bottles
5.1 Materials
Warning; If the sample is a highly corrosive fluid such as phosphate ester anti-flammable fluid, use a material that is determined to be compatible with the sample being taken, e.g. glass, to avoid corrosion and personal injury problems.
The material of the sample bottle should be compatible with the sample being taken, the temperature range should be compatible with the sample being taken, and colourless, transparent materials should be used to facilitate observation of the location and state of the sample. Materials that tend to polymerise or produce particles in the sample should not be used.
5.2 Appearance
Sampling bottles should have a smooth inner surface, a rounded bottom corner and a smooth opening to prevent retention of solid particles. Wide mouth, flat bottom bottles are preferred to facilitate cleaning, but frosted mouths should not be used.
5.3 Sealing
To facilitate transport and prevent secondary contamination, the mouth of the sampling bottle should be sealed. It is advisable to use the cap sealing method, both without the inner plug and no off the threaded cap sealing method, but also available with a gasket inside the cap sealing method.
5.4 Specifications
The specifications of the sampling bottle should be adapted to the type of particle contamination testing instrument sampler used and the volume of the liquid sample to be tested, and the general volume should not be less than 150 mL.
5.5 Cleanliness
6 Sampling principles
6.1 Pipeline Sampling
Warning: Sampling from high pressure lines is dangerous and should only be carried out by trained personnel. If the sample touches the skin during sampling, it may cause serious injury and medical attention should be sought as appropriate.
6.1.1 Take a sample from a main flow line in turbulent flow (see example in Figure 1) using a sampler that meets the following requirements
a) compatible with the fluid sample taken and with the operating pressure of the hydraulic system
b) allows the on/off of the sample flow to be controlled by a shut-off valve;
c) a pressure-reducing function which, when open, reduces the system pressure to atmospheric pressure at a minimum flow rate of 100 mL/min (preferably 500 mL/min), and the pressure-reducing device
The pressure reducing device should not alter the particle pressure distribution of the contaminants.
d) The inner diameter of the sampling tube should be 1.2 mm to 5 mms.
e) The sampling point should be located in the turbulent flow zone.
turbulent flow.
f) Be appropriate to the sampling method and particle contamination detector used.
(g) Repeatability and reproducibility of the sample taken
h) easy to use and leak-free
i) a rational internal structure, easy to rinse clean, with minimum contamination of its own and minimal deposition of particulate contamination when not in operation
Minimal deposition of particulate matter when not in operation.
6.1.2 The sampler should be connected from the upper part of the system pipeline, its axis should be approximately perpendicular to the system pipeline, and the sampling point should avoid the boundary layer of the system pipeline, and make the liquid flow vertically downwards.
6.1.3 A shut-off valve or a check valve with quick-change coupling should be fixed to the sampling point. To reduce the ingress of environmental contaminants, cover the outlet with a dust cap.
6.1.4 Operate the hydraulic circuit so that the particulate contamination is dispersed as evenly as possible throughout the hydraulic system.
6.1.5 When sampling, the shut-off valve should be in the fully open position to ensure a sampling flow rate of 100 mL/min to 500 mL/min. To reduce the sampling flow rate, it may be necessary to connect a small internal diameter line to the outlet of the shut-off valve depending on the pressure of the hydraulic system and the size of the shut-off valve, but the internal diameter of the line should be not less than 1.2 mm.
Note: When sampling for online analysis, the sampling flow rate may be lower than 100 mL./ min due to the limitation of the particle contamination testing instrument, which may cause the particles to settle in the pipeline and affect the testing results.
6.1.6 Install the sampler in a location that is easy to operate and away from environmental contamination.
6.2 Oil tank sampling
6.2.1 If it is not possible to install the sampler directly on the hydraulic system piping, the sample can be taken from the system's tank. Care should be taken to avoid the ingress of external contaminants when taking samples.
6.2.2 Samples should be taken from the central area of the fluid, away from areas where the fluid is stationary due to corners or baffles.
6.2.3 Select an opening above the tank level to allow access to the sampler. Ensure that the sampling end is inserted to a depth of h/2 below the liquid level by placing a reference mark on the sampler.
6.2.4 Carefully select the sampling method to ensure that the minimum amount of contaminants are introduced by the environment.
6.2.5 Figure 2 shows a sampling device that uses a vacuum to draw the liquid sample into the sampling bottle.
7 Sampling procedures
7.1 Sampling procedures for off-line analysis
8 Labelling
9 Labelling instructions
When this document is fully complied with, the following statement may be included in test reports, product samples and sales documents:
"Sampling method in accordance with GB/T 17489-2022 & Analysis of particle contamination in hydraulic drives , Extraction of fluid samples from working system lines".
Bibliography
