No-Shutdown Safety Valve Switching: TOSSKH Change-over Valve Solution

No-Shutdown Safety Valve Switching: TOSSKH Change-over Valve Solution

Complies with 3% Inlet Pressure Drop Standard | Dual-Valve Backup Design
Technical data switching valve
Type: Single-switch valve & Dual-switch valve
Set pressure: 0.2 - 400 barg / 2 - 5802 psig
Connection method: DN2 to DN40
DIN EN 1952
Connection method: NPS 1" to NPS 16
ASME B16.5
BODY Material: WCB, LCB, LCC, LF2, CF8, CF8M
Support special materials

Appurtenance:

no shutdown safety valve switching tosskh change over valve solution-1

Simplified Calculation Template for Safety Valve Capacity and Throat Diameter

1. Basic Parameter Input Section (Fill in according to actual working conditions)

Parameter Name	Symbol	Unit	Input Value	Remarks (Value Selection Instructions)
Medium Type	-	-		Optional: Gas/Liquid/Steam
Vessel Operating Pressure	Pw	MPa		Design pressure of the vessel under normal operation
Safety Valve Set Pressure	Po	MPa		Typically = 1.05~1.1 × Pw (per code requirements)
Safety Valve Back Pressure	Pb	MPa		Pressure on the discharge side (fill in 0 if no back pressure)
Medium Temperature	T	K		Absolute temperature (℃ + 273.15)
Medium Density (for Liquid)	ρ	kg/m³		Density of liquid at 20℃ (refer to medium property table)
Medium Molar Mass (for Gas)	M	kg/kmol		Molecular weight of gas (e.g., air = 29, nitrogen = 28)
Compressibility Factor (for Gas)	Z	-		Take 1 for ideal gas; check compressibility chart for high-pressure gas (usually 0.8~1.2)
Safety Valve Flow Coefficient	K	-		Provided by valve manufacturer (if no data: 0.6~0.7 for standard valves, 0.8~0.9 for high-efficiency valves)

2. Capacity Calculation Section (Select formula by medium type)
2.1 Liquid Medium Capacity Calculation
•Pressure Difference: ΔP = Po - Pb (MPa)
•Capacity Formula: Q_liquid = K × A × √(2×ΔP/ρ) (m³/h)
•Step-by-Step Calculation:
① ΔP = ______ (substitute Po and Pb values)
② √(2×ΔP/ρ) = ______
③ Temporarily assume A = 0.0001 m² (to be reversed later), Tentative Q_liquid = ______ m³/h
2.2 Gas Medium Capacity Calculation (Ideal Gas)
•Capacity Formula: Q_gas = K × A × Po × √(M/(T×Z)) × 3600 (m³/h)
•Step-by-Step Calculation:
① √(M/(T×Z)) = ______
② Po × √(M/(T×Z)) = ______
③ Temporarily assume A = 0.0001 m², Tentative Q_gas = ______ m³/h
2.3 Steam Medium Capacity Calculation (Simplified Formula)
•Capacity Formula: Q_steam = 0.5 × K × A × Po × 10⁶ / √T (kg/h)
•Step-by-Step Calculation:
① 10⁶ / √T = ______
② Po × 10⁶ / √T = ______
③ Temporarily assume A = 0.0001 m², Tentative Q_steam = ______ kg/h

3. Throat Diameter Calculation Section (Reverse minimum throat diameter from capacity)

Step	Calculation Content	Formula	Calculation Result
1	Required Minimum Capacity (Actual Demand)	Q_required = ______ m³/h (liquid/gas) or kg/h (steam)
2	Required Flow Area	A_required = Q_required / [“K×√(...)” term in the corresponding medium capacity formula]	A_required = ______ m²
3	Throat Diameter (Before Rounding)	d = √(4×A_required/π)	d = ______ mm
4	Standard Throat Diameter (After Rounding)	Select standard value ≥ d with reference to the table below	Final Throat Diameter = ______ mm

4. Set Pressure Test Data Column (SEO Keywords: Safety Valve 3-Round Set Pressure Test, 1.9MPa Pressure Actual Measurement Data)

Test Item	Test Pressure (MPa)	Pressure Holding Time (min)	Leakage (Bubbles/Minute)	Test Result	Remarks
Leak Test (Nitrogen)	1.71	5	10	Qualified	Back pressure during test: 0MPa
Air Tightness Test	0.2	1	No Leakage	Qualified	Test Medium: Nitrogen

5. Sealing Performance Test Data Column (SEO Keywords: Safety Valve Bubble Leak Test, 1.71MPa Sealing Pressure Verification)

Test Round	Required Set Pressure (MPa)	Actual Opening Pressure (MPa)	Pressure Deviation (%)	Adjustment Record (If Any)	Test Result
Round 1	1.9	1.91	0.50%	No Adjustment	Qualified
Round 2	1.9	1.91	0.50%	No Adjustment	Qualified
Round 3	1.9	1.91	0.50%	No Adjustment	Qualified
Average	1.9	1.91	0.50%		Qualified

6. Notes
1.After calculation, ensure: Flow area A of standard throat diameter ≥ Calculated A_required; otherwise, the capacity will be insufficient.
2.For real gas medium, correct the compressibility factor Z (cannot be ignored under high-pressure conditions).
3.For saturated steam, the simplified formula can be used directly; for superheated steam, multiply by a superheat correction factor (1.05~1.1).
4.If the flow coefficient K is not specified, consult the valve manufacturer first; use a conservative value (0.6) if no data is available to avoid undersizing.