GB/T 25178-2020 in English
VALIDReduced-pressure type backflow preventer
- Issued on:2020-12-14
- Implemented on:2020-12-14
- File Format:PDF
- Delivery:Via email within 5 business days
Price(USD)：
$310.00
$301.00
$301.00
《GB/T 25178-2020减压型倒流防止器》由TC434（全国城镇给水排水标准化技术委员会）归口，主管部门为住房和城乡建设部。
Introduction
Core changes in the standard revision
| Technical elements | 2010 edition | 2020 edition |
|---|---|---|
| Definition of terms | 5 basic terms | New definition of "starting discharge pressure difference", deleted 2 redundant terms |
| Structural requirements | Dispersed clauses | Integrated into Chapter 5, strengthen the arrangement requirements of detection ball valves |
| Performance indicators | 7 basic requirements | Add 4 new indicators such as cycle test and hygiene requirements |
Analysis of key technical requirements
1. Structural design specifications
The standard requires that the backflow preventer must be equipped with:
- 2 independently acting check valves (without mechanical linkage)
- 4 equal-diameter detection ball valves (position see standard clause 5.2.3)
- Equipment above DN50 must be equipped with a removable valve cover
2. Key performance indicators
Typical case: During the factory inspection of a DN100 backflow preventer, when the water inlet chamber pressure P1=0.2MPa:
- The intermediate chamber pressure P2=0.6MPa class=instrument>P2needs ≤0.186MPa (pressure difference ΔP ≥ 14kPa)
- The starting pressure difference of the drain valve should be ≥14kPa
- The pressure loss under zero flow state is ≤60kPa
Implementation suggestions
1. Control of the manufacturing process
Key points:
- The shell wall thickness should meet the requirements of GB/T26640
- Rubber seals must pass GB/T21873 sanitary certification
- Painting adhesion ≥8MPa (GB/T5210 test)
2. Inspection precautions
Type test needs to be completed:
- 5000 opening and closing cycle tests (25%-100% flow classification)
- 50kPa vacuum siphon test (lasting 5min)
- Pressure fluctuation ±10kPa stability verification
Sample only — not a preview of GB/T 25178-2020
Loading PDF document...
Error loading PDF. Please make sure the file is valid and try again.
We also recommend
-
GB/T 32063-2015/XG1-2018 in English
Customer service for public of urban water supply, includes Amendment 1
2015-10-13 -
GB/T 37621-2019 in English
Buried type butterfly valve
2019-06-04 -
GB/T 38594-2020 in English
Water supply devices with superimposing pipe pressure
2020-03-31
