ARCHIVE
january 2023
december 2022
november 2022
october 2022
september 2022
august 2022
july 2022
june 2022
may 2022
april 2022
march 2022
february 2022
december 2021
november 2021
october 2021
september 2021
august 2021
july 2021
april 2021
march 2021
february 2021
january 2021
december 2020
november 2020
october 2020
september 2020
august 2020
july 2020
june 2020
may 2020
april 2020
march 2020
february 2020
january 2020
december 2019
october 2019
august 2019
may 2019
march 2019
february 2019
january 2019
december 2018
november 2018
october 2018
september 2018
august 2018
july 2018
april 2018
march 2018
february 2018
january 2018
december 2017
november 2017
october 2017
september 2017
august 2017
july 2017
june 2017
may 2017
april 2017
march 2017
february 2017
january 2017
december 2016
november 2016
october 2016
september 2016
august 2016
july 2016
june 2016
may 2016
april 2016
march 2016
february 2016
january 2016
december 2015
november 2015
october 2015
september 2015
august 2015
july 2015
june 2015
may 2015
april 2015
march 2015
february 2015
january 2015
december 2014
november 2014
october 2014
september 2014
august 2014
july 2014
june 2014
may 2014
april 2014
march 2014
february 2014
january 2014
december 2013
november 2013
october 2013
september 2013
august 2013
july 2013
june 2013
may 2013
april 2013
march 2013
february 2013
january 2013
april 2011

Operation and assembly of the safety valves

The safety valves are components that are able to increase the safety level of a thermo-hydraulic system to prevent that there is an extremely dangerous pressure in the system. In Italy and in Europe the use and installation are defined by the "pressure equipment directive" which specifies that it is necessary to adopt these safety release valves on pressure vessels such as boilers, pressure cookers and pipes. In the United States, on the other hand, the reference regulations are "ASME Boiler and Pressure Vessels Code".


What are the main sectors of application?

Safety valves can cover many uses and have a very wide range of diffusion. The main fields are:
- Energy, both for storage and transport;
- Petrochemical;
- Naval;
- Chemical and pharmaceutical industries;
- Oil and gas plants.


Operating principle of safety valves

Generally, safety valves have an inlet connected to the process and a discharge connection that can be opened to the atmosphere or connected to a recovery pipe.
The valves have a mouthpiece on the inside with a section that shrinks to the end. It forms a ring on which acts a spring-loaded shutter which can be adjusted by means of a screw with plate located in the upper part of the valve. Both the shutter and the ring surfaces are polished and ground, ensuring an excellent metal-to-metal seal.
When the process exerts its pressure, through the mouthpiece, on the shutter, a force is generated due to the resistant action of the spring. At a certain point, however, the pressure exceeds the resistance force and, therefore, the shutter is forced to rise and the fluid passes radially. There is a downward projection that conveys the fluid at very high speed and causes such a force on the shutter to generate the complete opening of the valve.
If, on the contrary, the pressure drops below a certain level, the valve performs the opposite mechanism and closes.


How are safety valves installed?

The assembly of safety valves can be done either horizontally or vertically. The important thing is to avoid placing them upside down, to avoid an accumulation of impurities that could damage the sealing plate over time. Furthermore, there must not be any interception valves between the safety valve and the device to be protected.
Another important rule concerns the discharge pipe:
- It must not interfere with the regular operation of the valve;
- The diameter must be at least equal to that of the outlet fitting.


The maintenance of the safety valves

Safety valves must be checked periodically to make sure they are working properly. For this reason, sometimes, there is a lever that allows to control the locking but is not able to provide information on the calibration. 
For these reasons, the valves must be disassembled and checked on calibration benches, checking by applying an increasing pressure of air.

19/08/2019


See also
19/04/2013 Safety provisions of the valves offered by Gnali Bocia Safety valves are designed to work on contact with hot water accumulation systems for sanitary installations

19/11/2014 Installing the safety valve Some criteria for installing the safety valve in the system

19/11/2020 The operating principles of water pressure reducers Robust solutions applied to water pressure reducers in order to safeguard your system

19/08/2022 Safety valve and assembly onto the water heater The safety and check valve must be fitted onto the water heater inlet for it to operate correctly

19/02/2021 The operation of shut-off valves The shut-off valve allows correct dosage of fuel to the heat generator


I contenuti di questo sito non hanno carattere di periodicità e non rappresentano 'prodotto editoriale'.