Yoshitake AL-300 series safety relief valves are used in small boilers, various pressure vessels, instrumentation devices, pumps, and at the outlet of pressure reducing valves. The series includes the AL-300 and AL-301 models for steam, as well as the AL-300T and AL-301T models for air, water, oil, and other non-dangerous fluids. These closed-type valves feature a ductile cast iron body and a simple structure that is easy to maintain and adjust.

Features

• Simple in structure and easy to maintain.
• Can be adjusted easily.
• The AL-300T and the AL-301T for liquid/gas use can close completely since a PTFE disc is used between their valve and valve seat.
• The trim parts (valve, valve seat) of the AL-301 are made of stainless steel with outstanding corrosion resistance.

Specifications

WARNING

Please confirm that the indications on the product correspond with the specifications of the ordered product model before use. If they are different, please contact the manufacturer without using the product.

AL-300 and AL-301 (For Steam)

Model	AL-300	AL-301
Structure	Closed type	Closed type
Application	Steam	Steam
Working pressure	0.05-1.0 MPa	0.05-1.6 MPa
Max. temperature	220℃	220℃
Valve case, spring case	Ductile cast iron	Ductile cast iron
Valve, valve seat	Cast bronze	Stainless steel
Connection	JIS 10K FF flanged	JIS 10K FF flanged

Note: JIS 16K FF flanged when working pressure is more than 1.0 MPa.

AL-300T and AL-301T (For Air, Water, Oil, Non-dangerous fluid)

Model	AL-300T	AL-301T
Structure	Closed type	Closed type
Application	Air, Cold and hot water, Oil, Other non-dangerous fluid	Air, Cold and hot water, Oil, Other non-dangerous fluid
Working pressure	0.05-1.0 MPa	0.05-1.3 MPa
Max. temperature	150℃	150℃
Valve case, spring case	Ductile cast iron	Ductile cast iron
Valve, valve seat	Cast bronze and PTFE	Stainless steel and PTFE
Connection	JIS 10K FF flanged	JIS 10K FF flanged

Note: JIS 16K FF flanged when the working pressure is more than 1.0 MPa. Please contact the manufacturer if working pressure is between 1.31 MPa and 1.6 MPa.

Dimensions and Weights

AL-300, AL-301

Nominal size	L (mm)	H (mm)	H₁ (mm)	d (mm)	Flow area (mm²)	Weight (kg)
15A	90	245	108	25	49.1	4.7
20A	90	245	108	25	49.1	5.0
25A	90	245	108	25	49.1	6.2
32A	91	285	115	37	107.6	8.6
40A	91	285	115	38	113.5	8.8
50A	105	311	132	50	196.4	12.6

AL-300T, AL-301T

Nominal size	L (mm)	H (mm)	H₁ (mm)	d (mm)	Flow area (mm²)	Weight (kg)
15A	90	245	108	29	66.1	4.7
20A	90	245	108	29	66.1	5.0
25A	90	245	108	29	66.1	6.2
32A	91	285	115	37	107.6	8.6
40A	91	285	115	37	107.6	8.8
50A	105	311	132	50	196.4	12.6

Operation

Opening operation

As the inlet pressure approaches the opening pressure, the force of fluid pushing up the valve approaches the force pressing down the valve. The safety relief valve starts to discharge when the inlet pressure reaches around 3% below the opening pressure, and the fluid accumulates gradually on the pressure groove. When the fluid pressure reaches the opening pressure, the valve pops.

Closing operation

Since the inlet pressure of the safety relief valve decreases when the fluid is released into the atmosphere by the pop action of the valve, the fluid lift force is lowered. At this point, the repelling force of the spring becomes larger than the force of fluid lift and thus the valve closes.

Installation

DANGER

Do not install any closing device such as a stop valve at inlet and outlet sides of the product. Lead outlet pipe to a place where there is no risk of physical damage even if fluid blows out. Failure to follow this notice may result in injury and scalds.

WARNING

Do not disassemble the product unnecessarily. Do not apply viscous fluid that may make fixation of the valve and valve seat.

Installation Guidelines:

1. Before installing the product, remove foreign substances and scale from the piping.
2. Match the direction of fluid flow with the inlet and outlet of the product respectively.
3. Install the product in a way that excessive load, torque, or vibration cannot be applied to the product.
4. Inner diameters of pipe mount and of exhaust pipe shall be equal to or larger than those of each inlet and outlet of the product.
5. Install the product in a posture in which the stem of the adjusting screw is vertical to the ground and the cap faces upward. Preferably attach the product directly to a pressure vessel.

Operating Procedure

WARNING

Do not apply the product to devices which do not allow any valve seat leakage. The product has allowable valve seat leakage and does not close completely (the valve seat leakage cannot be zero). Do not touch the product with bare hands when fluid is hot.

Opening pressure adjustment

1. Turn the cap counterclockwise and remove it.
2. Loosen the lock nut by turning it counterclockwise using a spanner.
3. To increase the set pressure, turn the adjusting screw clockwise using a spanner.
4. To decrease the set pressure, turn the adjusting screw counterclockwise using a spanner.
5. After adjustment is completed, tighten the lock nut and then the cap.

Maintenance

DANGER

Disassembly and inspection must be done by an experienced professional. Completely discharge inside pressure from the product, piping and equipment prior to disassembly or inspection. When fluid is hot, cool down the product to the condition that it can be touched with bare hands.

Disassembly

1. Remove the cap and loosen the lock nut. Measuring the height from the top surface of the adjusting screw to that of the spring case before disassembly can provide a guide for reassembly.
2. Loosen the adjusting screw by turning it counterclockwise to the condition that the spring is free of load.
3. Remove the spring case by loosing the stud bolts and nuts. Then remove the top spring plate, spring, bottom spring plate and the valve.

Reassembly

Clean the parts before reassembling. Reassemble them in the reverse order of disassembly.