1.1 The filters listed in this standard are applicable to the liquid and gas materials produced in chemical industry, petrochemical industry, light industry and the like, for the purpose of filtering solid impurities. They are generally installed at the inlet of pump, compressor, or the pipeline in front of flowmeter in order to protect this kind of equipment or instrument.
1.2 This standard includes two series: metric series and inch series. Metric series covers three pressure classes, i.e. 1.0, 2.5 and 4.0MPa; inch series is divided into two pressure classes, i.e. 150 and 300Lb (2.0 and 5.0MPa).
In metric series, the pressure class of pointed and flat-roofed cone-shaped filter starts from 0.6MPa, i.e. 0.6, 1.0 and 2.5MPa.
1.3 Main structural materials of filters in this standard are cast iron, carbon steel, low-alloy steel and austenitic stainless steel, with the working temperature range of -20~300℃ for cast iron, -20~400℃ for carbon steel, -40~400℃ for low-alloy steel and -196~400℃ for stainless steel.
2 Application Scope
2.1 Nominal diameter
15~600mm (?″~24″)
2.2 Working temperature
-196~400℃
2.3 Working pressure
Metric series: ≤4.0MPa
Inch series: ≤4.64MPa
Where the working temperature is greater than 200℃, filter shall be selected according to the corresponding relationship of working pressure with working temperature. The maximum working pressures under different working temperatures are detailed in Tables 1 and 2.
Table 1 Corresponding Relationship of Working Temperature with
Working Pressure for Metric Series Filter
......
......
2.4 Working medium
Main applicable materials are:
Weak corrosive materials in chemical and petrochemical production. Such as water, ammonia, oil product and hydrocarbon.
Corrosive materials in chemical production. Such as caustic soda, soda ash, concentrated and dilute sulphuric acid, nitric acid, acetic acid and fatty acid.
Low temperature materials in refrigerating and air separation production. Such as liquid methane, liquid nitrogen, liquid oxygen and all kinds of cryogens.
Materials with hygiene requirements in light industrial food and pharmaceutical production. Such as beer, drink, milk product, syrup and medical supplies.
Generally, filters of different materials shall be selected according to the corrosion of medium to materials.
2.5 Size of interceptive solid particles
In this standard, filters use stainless steel wire mesh of 30 meshes/inch as standard wire mesh, which may intercept the solid particles with particle size greater than or equal to 614μm.
3 Classification
HG/T 21637-1991 The following standards are cited：
