The Yoshitake AL-400L and AL-400TL are lever-type safety relief valves typically used on the outlet side of pressure reducing valves or small pressure vessels. The AL-400L is an open type designed for steam applications, while the AL-400TL is a closed type suitable for air, water, oil, and other non-dangerous fluids. Both models feature a durable ductile cast iron (FCD450) body and stainless steel trim for reliable performance.

Features

• Lever type safety relief valve.
• Typically used on the outlet side of pressure reducing valves or small pressure vessels.
• Trim: stainless steel.

Specifications

Model	AL-400L	AL-400TL
Structure	Open type with lever	Closed type with lever*1
Nominal size	15~50A	15~50A
Application fluid	Steam	Air, water, oil and other non-dangerous fluids
Working pressure	0.05~1.6 MPa	0.05~1.3 MPa
Temperature	220°C	5~120°C
Connection	JIS 10K FF Flanged2 / JIS 16K FF Flanged2	JIS 10K FF Flanged2 / JIS 16K FF Flanged2
Body / Spring case	Ductile cast iron (FCD450)	Ductile cast iron (FCD450)
Valve / Valve seat	Stainless steel	Stainless steel (With PTFE valve disc)

*1 Closed type is a structure that does not allow any part of the blown fluid to be discharged to the outside except at the outlet. *2 JIS 16K FF flanges are used when the applicable pressure exceeds 1.0 MPa.

Dimensions and Weights

Nominal size	L (mm)	H1 (mm)	H (mm)	Weight (kg)
15A	90	108	282	5.4
20A	90	108	282	5.7
25A	90	108	282	6.9
32A	91	115	325	9.6
40A	91	115	325	9.8
50A	105	132	351	13.6

Structure and Parts

No.	Name of Parts	Material
1	Spring Case	Ductile Cast Iron (FCD450)
2	Body	Ductile Cast Iron (FCD450)
3	Valve Seat	Stainless Steel (SUS304)
4	Valve / Valve · P	Cast Stainless Steel (SCS13 or SCS14A)
7	Spring	Piano Wire or Steel Wire (SWP or SWC)
8	Cap	Bronze (CAC406)
9	Adjusting Screw	Brass (C3604)
10	Lock Nut	Brass (C3604)
11	Stud Bolt & Nut	Steel
12	Gasket	Non-Asbestos
13	Gasket	Non-Asbestos
14	Name Plate	Aluminium (A1100P)
15	Spindle	Stainless Steel (SUS304)
17	Lever	Stainless Steel (SUS430)
18	Connecting Rod	Brass (C3604)
20	Pin	Stainless Steel (SUS)

Figure: Valve Seat of AL-400TL (Same as AL-400L except for the valve seat).

Certified Capacity

AL-400L (For Steam)

Saturation temperature, Pressure vessel structure standard (kg/h)

Nominal size \ Pressure MPa	0.1	0.2	0.3	0.5	0.7	1.0	1.3	1.6
15A, 20A, 25A	50	73	98	148	196	268	340	411
32A	110	160	214	324	430	588	745	902
40A	116	168	226	342	454	620	786	951
50A	201	292	392	592	785	1073	1360	1646

AL-400TL (For Air)

20℃, Pressure vessel structure standard (kg/h)

Nominal size \ Pressure MPa	0.1	0.2	0.3	0.5	0.7	1.0	1.3
15A, 20A, 25A	109	159	213	322	432	595	759
32A, 40A	178	259	347	525	703	969	1236
50A	325	473	635	959	1283	1769	2256

AL-400TL (For Water)

Accumulation: 25%, Yoshitake standard (m³/h)

Nominal size \ Pressure MPa	0.1	0.2	0.3	0.5	0.7	1.0	1.3
15A, 20A, 25A	1.1	1.6	2.0	2.6	3.1	3.7	4.2
32A, 40A	1.9	2.7	3.3	4.2	5.5	6.0	6.9
50A	3.5	4.9	6.0	7.8	9.2	11.0	12.6

(Note: Capacity tables above show selected pressure points. Refer to full documentation for intermediate values).

Operation

1. Initial closed state: When the pressure at the inlet side of the safety relief valve is lower than the opening pressure, the valve / valve · P are held down by spring force and the valve is closed.
2. Discharge: When the pressure on the inlet side increases and approaches the opening pressure, the force of the fluid trying to push up the valve approaches the force holding it down, causing it to start discharging. This gradual buildup of pressure in the pressure groove leads to a vigorous popping operation when the predetermined opening pressure is reached.
3. Closing: When the valve is popped and fluid is released to the atmosphere, the pressure on the inlet side decreases, and the force of the spring prevails and closes the valve.

Installation and Precautions

WARNING

• Do not use this product for equipment or devices that do not allow valve seat leakage. This product has valve seat leakage within the allowable value and cannot be completely closed.
• Do not install any closing device such as a stop valve at the inlet or outlet side.
• Connect a discharge pipe and a drain pipe to the outlet side of the product, and lead it to a place where there is no risk of physical damage even if the fluid blows out.
• The set pressure cannot be adjusted (changed).
• Do not disassemble the product.

CAUTION

• The product should be installed in a vertical position with the cap facing upward.
• Since there is a risk of drain water or rainwater accumulating in the discharge pipe, be sure to install a drain at a location where it can be removed.
• The internal diameters of the mounting pipe stand and discharge pipe should be equal to or greater than the inlet and outlet diameters, respectively.

Discharge Pipe Installation

For steam applications, install the discharge pipe and expansion joints to ensure that the stress caused by the thermal expansion of the equipment and the thermal effects of the safety relief valve discharge does not affect the safety relief valve. The piping diameter of the discharge pipe should be at least equal to the outlet diameter of the product, and the piping should be designed to prevent back pressure.

Maintenance

Daily and Periodic Inspection

• Daily inspection (Once per day): Check for external leakage of internal fluid. Ensure there is no leakage from the outlet side of the safety relief valve at normal pressure.
• Periodic inspection (Once per month): Check for looseness in piping, cap, and stud bolts. Perform an operation check by either increasing fluid pressure to the set pressure or lifting the lever when pressure is at 75% or more of the set pressure.

Lever Lifting Procedure: Position the lever perpendicular to the pin. If the lever is in a horizontal position, it may not lift or could be damaged when lifted. Lift the lever to initiate the discharge operation. Do not stand in front of the discharge pipe.

Troubleshooting

Fault Condition	Cause	Countermeasures/Actions
Leakage from the outlet side	Debris or scale is lodged between the valve and valve seat.	Operate the safety relief valve to remove debris. If leakage persists, contact us.
	Contact surface of the valve seat is damaged.	The product needs to be replaced.
	Misoperation due to vibration in the piping.	Cannot be used in systems with excessive vibration.
External leakage	Gaskets are deteriorated or damaged.	Gaskets need to be replaced.
Operates at pressure lower than set pressure	Product specification does not match operating conditions.	Check set pressure on nameplate. Replace if conditions differ.
	Pressure gauge is faulty.	Calibrate or replace the pressure gauge.
Does not operate even at set pressure	Sliding parts between valve and valve seat are not moving smoothly.	Product needs to be returned, disassembled, and cleaned.
	Back pressure in the outlet piping.	Remove back pressure. Modify piping layout.
Valve remains in a continuously discharged state	Normal pressure is higher than the reseating pressure.	Increase the difference between set pressure and normal pressure.
Lever cannot be lifted	Inlet side pressure is low.	Increase inlet pressure to at least 75% of the set pressure.
	Lever is not perpendicular to pin.	Adjust the lever to a perpendicular position relative to the pin and lift it.