2025-5-19 18.97.14.85
Code of China Chinese Classification Professional Classification ICS Classification Latest News Value-added Services

Position: Chinese Standard in English/GB/T 18688-2023
GB/T 18688-2023   Agricultural irrigation equipment—Pressure losses in irrigation valves—Test method (English Version)
Standard No.: GB/T 18688-2023 Status:valid remind me the status change

Email:

Language:English File Format:PDF
Word Count: 14500 words Price(USD):360.0 remind me the price change

Email:

Implemented on:2024-6-1 Delivery: via email in 1~3 business day
,,
Standard No.: GB/T 18688-2023
English Name: Agricultural irrigation equipment—Pressure losses in irrigation valves—Test method
Chinese Name: 农业灌溉设备 灌溉阀的压力损失 试验方法
Chinese Classification: B91    Farming machinery and tools
Professional Classification: GB    National Standard
ICS Classification: 65.060.35 65.060.35    Irrigation and drainage equipment 65.060.35
Issued by: SAMR; SAC
Issued on: 2023-11-27
Implemented on: 2024-6-1
Status: valid
Superseding:GB/T 18688-2012 Agricultural irrigation equipment—Pressure losses in irrigation valves—Test methed
Language: English
File Format: PDF
Word Count: 14500 words
Price(USD): 360.0
Delivery: via email in 1~3 business day
GB/T 18688-2023 Agricultural irrigation equipment - Pressure losses in irrigation valves - Test method 1 Scope This document applies to manually-activated valves only. This document specifies a test method for determining the pressure loss in agricultural irrigation valves under steady-state conditions when water flows through them. The scope and accuracy of the valve performance specifications presented will assist agricultural irrigation system designers in comparing pressure losses through various types of valves. The measurement of pressure losses provides a means for determining the relationship between pressure loss and flow rate through the valve. This document also describes the method of reporting pertinent test data. No attempt is made to define product use, design or applications. The test method is suitable for valves with equal inlet and outlet nominal sizes. 2 Normative references There are no normative references in this document. 3 Terms and definitions For the purposes of this document, the following terms and definitions apply. 3.1 nominal size DN conventional numerical designation used to indicate the size of an irrigation valve 3.2 volume flow rate flow rate qV volume of water flowing through the valve per unit time 3.3 pressure loss Δp difference in pressure due to water flow between two specified points in a system or in part of a system 3.4 piping pressure loss Δpp pressure loss in the upstream and downstream portions of the test bench piping between the pressure taps, but excluding the pressure loss in the valve tested (see 5.4.4) 3.5 bench pressure loss Δpb head loss between the pressure taps upstream and downstream from the measurement area without the device being tested 3.6 valve pressure loss Δpv pressure loss in the valve tested 3.7 reference velocity νref velocity of flow through the valve calculated from the actual flow rate through the valve divided by the reference cross-sectional area of the valve 3.8 steady-state flow state of flow where the flow rate through a cross-section does not vary with time 3.9 valve flow coefficient Kv number equal to the flow rate of water, in cubic metres per hour (m3/h), that will flow through a fully open valve with a one bar pressure loss across the valve 3.10 flow resistance coefficient ζ coefficient used in non-dimensional presentation of valve loss 4 Test installation 4.1 Permissible deviation of measuring devices The permissible deviation of the reading indicated on the measuring devices from the actual value shall be as follows: flow rate: ± 2 % differential and actual pressure: ± 2 % temperature: ± 1 °C The measuring devices shall be calibrated according to the existing calibration rules in the country performing the test. 4.2 Test equipment 4.2.1 Piping Upstream and downstream piping shall be the same diameter as that of the test valve connection. The lengths of the straight, uniform-bore pipe shall be as specified in Figure 1. The inside surface of the piping shall be free of flaking rust, mill scale and irregularities which might cause excessive turbulence. In that part of the test apparatus shown within the frame, in Figure 1, the order of the fittings/devices shown in the key and the distances between them shall be adhered to, with the exception that the lengths indicated as 2d and 10d shall be understood to be the minimum allowable lengths. 4.2.2 Throttling valve A downstream throttling valve shall be used to control the flow through the test specimen. There are no restrictions on the size or type of this valve. The throttling valve shall be located downstream of the downstream pressure tap (used for measuring bench pressure). 4.2.3 Flow measuring device Locate the measuring device at the head of the system. If an open measuring device (such as a calibrated volumetric tank) is used, it shall be located at the downstream end of the assembly, i.e. downstream of the downstream throttling valve. The flow-measuring device shall be installed in accordance with the specific installation instructions and, where applicable, shall be installed with the required length of straight piping before and after the device. The accuracy of the measuring device shall be ± 2 %. 4.2.4 Pressure differential measuring device Any device capable of measuring pressure differential with acceptable accuracy may be used. 4.2.5 Pressure taps Pressure taps (see Figure 2) shall be provided on piping for measurement of static pressure, and spaced as shown in Figure 1. The drilling centreline of the taps shall intersect the centreline of the pipe perpendicularly, as shown in Figure 2. The diameter shall depend on the DN of the valve, see Table 1. The length, l, of the tap bore shall be not less than twice the diameter of the bore. For thin-walled pipes where the wall thickness is less than 2d1 , a boss may be added to the pipe wall where the pressure taps are to be located (see Figure 2). Pressure taps shall be free of burrs and other irregularities and the inside wall of the piping shall be machine-finished. For pipes of 50 mm diameter and larger, four taps shall be made, situated 90° ± 5° apart on the circumference so that no tap is located on the lowest point of the pipe circumference. For pipe diameters of less than 50 mm, two taps will suffice. All taps, whether two or four in number, shall be connected by a conduit whose bore shall not be less than two pressure-tap cross-sections. The pressure taps shall provide appropriate values of d1 and l, and may be made as illustrated in Figure 2.
Code of China
Standard
GB/T 18688-2023  Agricultural irrigation equipment—Pressure losses in irrigation valves—Test method (English Version)
Standard No.GB/T 18688-2023
Statusvalid
LanguageEnglish
File FormatPDF
Word Count14500 words
Price(USD)360.0
Implemented on2024-6-1
Deliveryvia email in 1~3 business day
Detail of GB/T 18688-2023
Standard No.
GB/T 18688-2023
English Name
Agricultural irrigation equipment—Pressure losses in irrigation valves—Test method
Chinese Name
农业灌溉设备 灌溉阀的压力损失 试验方法
Chinese Classification
B91
Professional Classification
GB
ICS Classification
Issued by
SAMR; SAC
Issued on
2023-11-27
Implemented on
2024-6-1
Status
valid
Superseded by
Superseded on
Abolished on
Superseding
GB/T 18688-2012 Agricultural irrigation equipment—Pressure losses in irrigation valves—Test methed
Language
English
File Format
PDF
Word Count
14500 words
Price(USD)
360.0
Keywords
GB/T 18688-2023, GB 18688-2023, GBT 18688-2023, GB/T18688-2023, GB/T 18688, GB/T18688, GB18688-2023, GB 18688, GB18688, GBT18688-2023, GBT 18688, GBT18688
Introduction of GB/T 18688-2023
GB/T 18688-2023 Agricultural irrigation equipment - Pressure losses in irrigation valves - Test method 1 Scope This document applies to manually-activated valves only. This document specifies a test method for determining the pressure loss in agricultural irrigation valves under steady-state conditions when water flows through them. The scope and accuracy of the valve performance specifications presented will assist agricultural irrigation system designers in comparing pressure losses through various types of valves. The measurement of pressure losses provides a means for determining the relationship between pressure loss and flow rate through the valve. This document also describes the method of reporting pertinent test data. No attempt is made to define product use, design or applications. The test method is suitable for valves with equal inlet and outlet nominal sizes. 2 Normative references There are no normative references in this document. 3 Terms and definitions For the purposes of this document, the following terms and definitions apply. 3.1 nominal size DN conventional numerical designation used to indicate the size of an irrigation valve 3.2 volume flow rate flow rate qV volume of water flowing through the valve per unit time 3.3 pressure loss Δp difference in pressure due to water flow between two specified points in a system or in part of a system 3.4 piping pressure loss Δpp pressure loss in the upstream and downstream portions of the test bench piping between the pressure taps, but excluding the pressure loss in the valve tested (see 5.4.4) 3.5 bench pressure loss Δpb head loss between the pressure taps upstream and downstream from the measurement area without the device being tested 3.6 valve pressure loss Δpv pressure loss in the valve tested 3.7 reference velocity νref velocity of flow through the valve calculated from the actual flow rate through the valve divided by the reference cross-sectional area of the valve 3.8 steady-state flow state of flow where the flow rate through a cross-section does not vary with time 3.9 valve flow coefficient Kv number equal to the flow rate of water, in cubic metres per hour (m3/h), that will flow through a fully open valve with a one bar pressure loss across the valve 3.10 flow resistance coefficient ζ coefficient used in non-dimensional presentation of valve loss 4 Test installation 4.1 Permissible deviation of measuring devices The permissible deviation of the reading indicated on the measuring devices from the actual value shall be as follows: flow rate: ± 2 % differential and actual pressure: ± 2 % temperature: ± 1 °C The measuring devices shall be calibrated according to the existing calibration rules in the country performing the test. 4.2 Test equipment 4.2.1 Piping Upstream and downstream piping shall be the same diameter as that of the test valve connection. The lengths of the straight, uniform-bore pipe shall be as specified in Figure 1. The inside surface of the piping shall be free of flaking rust, mill scale and irregularities which might cause excessive turbulence. In that part of the test apparatus shown within the frame, in Figure 1, the order of the fittings/devices shown in the key and the distances between them shall be adhered to, with the exception that the lengths indicated as 2d and 10d shall be understood to be the minimum allowable lengths. 4.2.2 Throttling valve A downstream throttling valve shall be used to control the flow through the test specimen. There are no restrictions on the size or type of this valve. The throttling valve shall be located downstream of the downstream pressure tap (used for measuring bench pressure). 4.2.3 Flow measuring device Locate the measuring device at the head of the system. If an open measuring device (such as a calibrated volumetric tank) is used, it shall be located at the downstream end of the assembly, i.e. downstream of the downstream throttling valve. The flow-measuring device shall be installed in accordance with the specific installation instructions and, where applicable, shall be installed with the required length of straight piping before and after the device. The accuracy of the measuring device shall be ± 2 %. 4.2.4 Pressure differential measuring device Any device capable of measuring pressure differential with acceptable accuracy may be used. 4.2.5 Pressure taps Pressure taps (see Figure 2) shall be provided on piping for measurement of static pressure, and spaced as shown in Figure 1. The drilling centreline of the taps shall intersect the centreline of the pipe perpendicularly, as shown in Figure 2. The diameter shall depend on the DN of the valve, see Table 1. The length, l, of the tap bore shall be not less than twice the diameter of the bore. For thin-walled pipes where the wall thickness is less than 2d1 , a boss may be added to the pipe wall where the pressure taps are to be located (see Figure 2). Pressure taps shall be free of burrs and other irregularities and the inside wall of the piping shall be machine-finished. For pipes of 50 mm diameter and larger, four taps shall be made, situated 90° ± 5° apart on the circumference so that no tap is located on the lowest point of the pipe circumference. For pipe diameters of less than 50 mm, two taps will suffice. All taps, whether two or four in number, shall be connected by a conduit whose bore shall not be less than two pressure-tap cross-sections. The pressure taps shall provide appropriate values of d1 and l, and may be made as illustrated in Figure 2.
Contents of GB/T 18688-2023
About Us   |    Contact Us   |    Terms of Service   |    Privacy   |    Cancellation & Refund Policy   |    Payment
Tel: +86-10-8572 5655 | Fax: +86-10-8581 9515 | Email: coc@codeofchina.com | QQ: 672269886
Copyright: TransForyou Co., Ltd. 2008-2040
 
 
Keywords:
GB/T 18688-2023, GB 18688-2023, GBT 18688-2023, GB/T18688-2023, GB/T 18688, GB/T18688, GB18688-2023, GB 18688, GB18688, GBT18688-2023, GBT 18688, GBT18688