Yoshitake AL-31H is a lift type, closed safety relief valve made of all stainless steel, offering high corrosion resistance and durability. Designed to handle steam, air, cold and hot water, oil, and other non-dangerous fluids, this model can be set at a maximum pressure of 2.0 MPa.

Features

• Safety relief valve of all stainless steel made, offering high corrosion resistance and durability in particular.
• AL-31H can be set at Max. 2.0 MPa.

Specifications

Model	AL-31H
Structure	Closed type *
Application	Steam, Air, Cold and hot water, Oil, Other non-dangerous fluids
Working pressure	1.0 - 2.0 MPa
Maximum temperature	220°C **
Connection	JIS 16K RF flanged, JIS 20K RF flanged
Nominal size	15 - 50A

* The structure in which the fluid is discharged only from the outlet. ** The maximum temperature is 150°C when using for water, oil, or other liquids (the fluid is liquid).

Dimensions and Weights

Nominal size	Dimension (mm) di x D x do	L	H1	H	Flow area (mm²)	Weight (kg)
15A	15 x 16 x 20	73	72	160	20.1	3.4
20A	20 x 21 x 25	77	74	163	34.6	4.5
25A	25 x 26 x 32	91	87	187	53.0	6.5
32A	32 x 33 x 40	96	92	238	85.5	8.1 (8.3)
40A	40 x 41 x 50	114	100	277	132.0	11.4 (11.7)
50A	50 x 51 x 65	116	107	315 (357)	204.2	15.0 (18.0)

• The above values in parentheses are the dimensions and weights of JIS 20K RF flanged.
• Screwed connection size of the outlet side is 1 size larger than the nominal size.

Certified Capacity Table for AL-31H

For Steam (at saturated temperature)

Capacity (Pressure vessel structure standard) [kg/h]

Nominal size	Blowout area [mm²]	1.0 MPa	1.1 MPa	1.2 MPa	1.3 MPa	1.4 MPa	1.5 MPa	1.6 MPa	1.7 MPa	1.8 MPa	1.9 MPa	2.0 MPa
15A	20.1	119	129	139	149	149	158	168	178	188	198	207
20A	34.6	206	222	239	256	256	273	290	306	324	340	357
25A	53.0	315	341	367	363	393	418	444	470	496	522	547
32A	85.5	509	550	592	634	634	675	716	758	800	842	883
40A	132.0	786	850	914	979	979	1042	1106	1171	1236	1300	1364
50A	204.2	1216	1315	1414	1514	1514	1612	1712	1811	1912	2011	2110

For Air (at 20˚C)

Capacity (Pressure vessel structure standard) [kg/h]

Nominal size	Blowout area [mm²]	1.0 MPa	1.1 MPa	1.2 MPa	1.3 MPa	1.4 MPa	1.5 MPa	1.6 MPa	1.7 MPa	1.8 MPa	1.9 MPa	2.0 MPa
15A	20.1	181	197	214	230	247	264	280	297	313	330	347
20A	34.6	311	340	368	397	426	454	483	511	540	568	597
25A	53.0	477	521	565	608	652	696	740	783	827	871	915
32A	85.5	770	841	911	982	1052	1123	1193	1264	1335	1405	1476
40A	132.0	1189	1298	1407	1516	1625	1734	1843	1952	2061	2170	2279
50A	204.2	1840	2008	2177	2345	2514	2682	2851	3020	3188	3357	3525

For Water (at 20˚C, accumulation: 25%)

Capacity (Yoshitake standard) [m³/h]

Nominal size	Blowout area [mm²]	1.0 MPa	1.1 MPa	1.2 MPa	1.3 MPa	1.4 MPa	1.5 MPa	1.6 MPa	1.7 MPa	1.8 MPa	1.9 MPa	2.0 MPa
15A	20.1	1.1	1.1	1.2	1.2	1.3	1.3	1.4	1.4	1.5	1.5	1.6
20A	34.6	1.9	2.0	2.1	2.2	2.3	2.3	2.4	2.5	2.6	2.6	2.7
25A	53.0	2.9	3.1	3.2	3.4	3.5	3.6	3.7	3.9	4.0	4.1	4.2
32A	85.5	4.8	5.0	5.2	5.5	5.7	5.9	6.1	6.2	6.4	6.6	6.8
40A	132.0	7.4	7.8	8.1	8.4	8.8	9.1	9.4	9.7	9.9	10.0	10.5
50A	204.2	11.5	12.0	12.6	13.1	13.6	14.1	14.5	15.0	15.4	15.8	16.3

[Example for water] When the set pressure is 2.0 MPa, and the valve size is 25A: The capacity is 4.2 m³/h, when the inlet pressure reaches 2.5 MPa (accumulation becomes 25%) after the fluid pressure reaches the set pressure of 2.0 MPa.

Operation

Blowout Operation

As the inlet pressure approaches the blowout pressure, the force of fluid pushing up the valve approaches the force of the spring pressing down the valve. The safety relief valve commences to blow when the inlet pressure reaches around 3% below the blowout pressure. The fluid accumulates gradually on the pressure groove and when the fluid pressure reaches the blowout 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 force of fluid lift is lowered. At this point, the repelling force of the spring becomes larger than the force of fluid lift and thus the valve closes. In addition, while the safety relief valve discharges, pressure of fluid entering into the back of the valve (back pressure) adds to the closing force.

Installation

WARNING

1. Do not install any closing device such as a stop valve at inlet or outlet sides of the product.
2. Do not apply the product to devices which do not allow any valve seat leakage.
3. Do not disassemble the product.
4. Install an exhaust pipe on the outlet side of the product, and lead it to a place where there is no risk of physical damage even if fluid blows out.
5. Do not apply viscous fluid that may make fixation of the valve and valve seat.
6. Connect the product to the pipes securely.

TIP

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 vertically with the cap facing upward.
4. Inner diameters of pipe mount and of exhaust pipe shall be more than those of each inlet and outlet of the product.

Pipe Mount and Exhaust Pipe

• Pipe mount should have sufficient strength and rigidity against stress which are induced by reaction force.
• Install the product vertically as close as possible to the can body and the header to prevent pressure loss in the pipe mount.
• Install exhaust pipe and drip pan elbow so that the product cannot be subject to the stress caused by thermal expansion of equipment.

Maintenance

WARNING

1. Do not touch the product/pipes with bare hands.
2. When checking the operation of the product, wear earplugs and stand clear of exhaust pipe end during inspection.
3. Do not remove the cap.

Daily and Monthly Inspection

Daily: Check for corrosion or crack on the product, leakage from the product under normal working pressure, and leakage from joints between the product and piping.

Monthly: Check that there is no loose piping at the inlet and outlet side of the product, and the cap is fastened securely. Check the operation of the product by raising fluid pressure to the set pressure.