Fengquan·spring type safety valve basic knowledge
Safety valve function principle:
The safety valve is used on pressure equipment and systems such as boilers and pressure vessels. It is used for protection equipment when overpressure (or negative pressure). When the safety valve protects the pressure equipment from abnormal pressure, the safety valve can be automatically opened and discharged. Effectively prevent the pressure of the protected pressure equipment from rising continuously, and the safety valve automatically closes when the pressure drops to the specified value. This protects the safe operation of equipment, containers or piping systems.
Operating parameters of spring type safety valve (GB12241)
Medium (use)
Performance parameter liquid medium
(container equipment)
Gas medium
(container equipment)
Steam powered boiler
DC boiler, reheater
And other steam equipment
Setting pressure deviation δ P s
When Ps <0.5MPa, δ Ps is ± 0.014
When Ps ≥ 0.5MPa, δ Ps is ± 3 c/o Ps
δ Ps is ± 0.014 when Ps <0.5MPa
δ Ps is ± 3 c/o Ps when Ps <0.5~2.3MPa
δ Ps is ± 0.07 at Ps=2.3~7.0MPa
δ Ps is ± 1 c/o Ps at Ps>7.0MPa
Discharge pressure P dr
1.2 × Ps
1.1 × Ps
1.03 × Ps
Opening and closing pressure difference â–³ Pbl
When Ps ≤ 0.3MPa, Δ Pbl ≤ 0.06
When Ps ≤ 0.2 MPa, Δ Pbl ≤ 0.03
When Ps ≤ 0.4 MPa, Δ Pbl ≤ 0.03
When Ps ≤ 0.4 MPa, Δ Pbl ≤ 0.04
When Ps > 0.3 MPa, Δ Pbl ≤ 20 c/o Ps
When Ps > 0.2 MPa, Δ Pbl ≤ 15 c/o Ps
When Ps > 0.4 MPa, Δ Pbl ≤ 7 c/o Ps
When Ps > 0.4 MPa, Δ Pbl ≤ 10 c/o Ps
Please specify the setting pressure range or setting pressure value MPa when ordering.
Nominal pressure MPa
Setting pressure range MPa
1.6
0.06~0.1
0.1 to 0.16
0.16~0.25
0.25~0.4
0.4 to 0.6
0.6 to 0.8
0.8 to 1.0
1.0 to 1.3
1.3 to 1.6
2.5
1.3 to 1.6
1.6 to 2.0
2.0 to 2.5
4.0
1.3 to 1.6
1.6 to 2.0
2.0 to 2.5
2.5 to 3.2
3.2 to 4.0
6.4
2.5 to 3.2
3.2 to 4.0
4.0～5.0
5.0～6.4
10.0
4.0～5.0
5.0～6.4
6.4~8.0
8.0~10.0
16.0
10~13
13~16
32.0
16~19
19~22
22~25
25~29
29~32
Main parts of spring type safety valve
Part Name Body Material Code
C
I
P
V
R
Valve body, valve cover WCB
ZGCr5M 0
ZG1Cr18Ni9Ti
ZG12CrMoV
1Cr18Ni12Mo2Ti
Disc and stem 2Cr13
1Cr18Ni9Ti
1Cr18Ni9Ti
1Cr18Ni9Ti
1Cr18N12Mo2T
Guide sleeve, back plate 2Cr13
1Cr18Ni9Ti
1Cr18Ni9Ti
1Cr18Ni9Ti
1Cr18N12Mo2T
Sealing surface material Cobalt-based alloy Cobalt-based alloy Cobalt-based alloy Cobalt-based alloy Cobalt-based alloy
Spring 50CrVA
50CrVA
50CrVA (coated with fluoroplastic)
50CrVA
50CrVA (coated with fluoroplastic)
Common faults and elimination methods for spring type safety valve operation
Cause analysis and elimination method
Valve Leakage • When the installation is correct, there may be debris between the sealing surfaces. The valve can be manually opened several times to flush the dirt.
• If the sealing surface is damaged, the sealing surface should be ground and repaired according to the degree of damage of the sealing surface.
• If the concentricity of the part is damaged due to improper assembly or pipe load, etc., it should be reassembled.
• The valve setting pressure is too close to the normal working pressure of the equipment, resulting in a seal surface that is too low pressure. Appropriate adjustments should be made to the opening pressure.
• The spring is slack and should be replaced due to high temperatures or corrosion. If it is not properly adjusted, it should be re-verified.
The valve is not open and closed. • If the adjustment ring is not properly adjusted, it should be adjusted again. The adjustment method is in accordance with the product instruction manual.
• Internal moving parts are jammed, which may be caused by improper assembly, dirt ingress or corrosion of parts. The cause should be eliminated.
• The discharge pipe is too resistant to open the valve and the discharge pipe should be horizontally arranged.
Turn on pressure value change • Caused by changes in operating temperature. It can be adjusted by properly tightening the adjusting screw, or a safety valve with a radiator can be used.
• Spring corrosion is caused by a spring covered with fluoroplastic.
• Caused by changes in back pressure
• Internal moving parts are stuck
Valve oscillation • If the valve discharge capacity is too large, the rated discharge should be close to the necessary discharge of the equipment.
• The inlet pipe is too small or too resistant.
• The discharge pipe is too resistant.
• If the spring stiffness is too large, a spring with less stiffness should be used.
• If the adjustment ring is not properly adjusted and the return pressure is too high, the position of the adjustment ring should be re-adjusted.
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