Yoshitake AL-4S and AL-4ST are full bore, lift type safety relief valves designed for high pressure gas testing applications. Mainly used at the outlet side of pressure reducing valves for alarming, compact boilers, pressure vessels, and instrumentation machines, these closed-type valves offer reliable performance and a non-leakage structure. The AL-4ST model incorporates a polytetrafluoroethylene (PTFE) disc in its valve seat, ensuring excellent airtightness for air, water, oil, and other non-dangerous fluids.

Features

• Mainly used at the outlet side of PRV for alarming, compact boilers, pressure vessels, or instrumentation machines.
• The AL-4ST features a PTFE material valve part, providing excellent airtightness at the valve seat.

Specifications

AL-4S

Structure	Closed type
Application	Steam
Working pressure	0.05-2.0 MPa
Maximum temperature	220℃
Material (Spring case)	Ductile cast iron
Material (Valve, valve seat)	Stainless steel
Connection	JIS 10K FF / 20K FF flanged

INFO

• Available with stainless steel.

AL-4ST

Structure	Closed type
Application	Air, Water, Oil, Other non-dangerous fluids
Working pressure	0.05-2.0 MPa
Maximum temperature	150℃
Material (Spring case)	Ductile cast iron
Material (Valve, valve seat)	Stainless steel (PTFE disc incorporated)
Connection	JIS 10K FF / 20K FF flanged

INFO

• When working pressure is more than 1.2 MPa (for 65A and 80A) or 1.0 MPa (for 100A and 125A), a metal-to-metal seating is incorporated in.
• Available with stainless steel (JIS 10K FF, JIS 20K FF).

(The shape of AL-4ST is slightly different.)

Dimensions and Weights

AL-4S

Nominal size	L (mm)	H1 (mm)	H (mm)	D (mm)	Flow area πDl (mm²)
65A	135	125	442	65	331.9
80A	135	135	457	75	441.8
100A	160	150	597	100	785.4

AL-4ST

Nominal size	L (mm)	H1 (mm)	H (mm)	D (mm)	Flow area πDe (mm²)
65A	135	125	444	65	331.9
80A	135	135	459	75	441.8
100A	160	150	599	100	785.4

Certified Capacity Tables

AL-4S (Steam)

For steam (saturation temperature) under Pressure Vessel Structure Standard (kg/h).

Pressure (MPa)	0.05	0.1	0.2	0.3	0.4	0.5	0.6	0.7	0.8	0.9	1.0	1.1	1.2	1.3	1.4	1.5	1.6	1.7	1.8	1.9	2.0
65A	263	340	493	663	834	1000	1165	1328	1489	1651	1814	1976	2138	2299	2461	2621	2783	2944	3108	3269	3430
80A	350	452	657	882	1111	1331	1550	1767	1983	2198	2415	2631	2846	3060	3276	3489	3704	3919	4138	4352	4566
100A	622	804	1168	1569	1975	2367	2756	3142	3525	3908	4294	4677	5059	5440	5825	6203	6586	6968	7357	7737	8118

AL-4ST (Air)

For air (20°C) under Pressure Vessel Structure Standard (kg/h).

Pressure (MPa)	0.05	0.1	0.2	0.3	0.4	0.5	0.6	0.7	0.8	0.9	1.0	1.1	1.2	1.3	1.4	1.5	1.6	1.7	1.8	1.9	2.0
65A	422	550	799	1073	1347	1621	1895	2169	2443	2717	2991	3264	3538	3812	4086	4360	4364	4908	5182	5456	5730
80A	562	732	1064	1428	1793	2158	2522	2887	3252	3616	3981	4346	4710	5075	5440	5804	6169	6534	6898	7263	7628
100A	999	1302	1891	2540	3188	3836	4484	5133	5781	6429	7077	7726	8374	9022	9671	10319	10967	11615	12264	12912	13560

AL-4ST (Water)

For water (accumulation: 25%) under Yoshitake standard (m³/h).

Pressure (MPa)	0.05	0.1	0.2	0.3	0.4	0.5	0.6	0.7	0.8	0.9	1.0	1.1	1.2	1.3	1.4	1.5	1.6	1.7	1.8	1.9	2.0
65A	4.1	5.9	8.3	10.2	11.8	13.2	14.5	15.6	16.7	17.7	18.7	19.6	20.5	21.3	22.1	22.9	23.6	24.4	25.1	25.8	26.4
80A	5.5	7.8	11.1	13.6	15.7	17.6	19.3	20.8	22.3	23.6	24.9	26.1	27.3	28.4	29.5	30.5	31.5	32.5	33.4	34.3	35.2
100A	9.9	14.0	19.8	24.2	28.0	31.3	34.3	37.0	39.6	42.0	44.3	46.4	48.5	50.5	52.4	54.2	56.0	57.8	59.4	61.1	62.6