Yoshitake AF-5 is a full bore safety valve designed with increased safety. It is compact and lightweight, approximately half the size of previous full bore type safety valves. The AF-5 features trim parts made of excellent quality materials, maintaining high performance through precision processing and heat treatment.

It incorporates a lift lever mechanism that allows a discharge inspection to be manually performed at more than 75% of the opening pressure. The related AF-5S model features an all-stainless steel construction for high corrosion resistance and durability.

Features

• Full bore safety valve with increased safety. Compact and lightweight.
• A material of excellent quality is used for the trim parts. High performance is maintained by precision processing and heat treatment.
• Corrosion-free due to corrosion-resistant material (the AF-5S is all stainless made, offering high corrosion resistance and durability).
• Due to lift lever mechanism a discharge inspection can be manually performed at more than 75% of the opening pressure.

Specifications

Model	AF-5	AF-5S
Structure	Open type with a lever	Open type with a lever
Application	Steam	Steam, Air, Other non-dangerous fluids
Working pressure	0.1-2.0 MPa	0.1-1.0 MPa
Maximum temperature	220°C	220°C
Material (Spring case)	Bronze	Stainless steel
Material (Valve, valve seat)	Stainless steel	Stainless steel
Connection	Inlet: JIS R screwed Outlet: JIS Rc screwed	Inlet: JIS R screwed Outlet: JIS Rc screwed

Dimensions and Weights

AF-5

Nominal size	Inlet diameter x Throat diameter x Outlet diameter (di x dt x do)	Valve seat diameter	Flow area $\frac{\pi}{4}dt^{2}(mm^{2})$	Lift ℓ (mm)	Dimension L (mm)	Dimension $H_1$ (mm)	Dimension H (mm)	Plug	Weight (kg)
20A	R 1 x 15 x Rc 1	18	176.6	3.3	38	61	136 (151)	R 1/8	1.3 (1.5)
25A	R 1-1/4 x 19 x Rc 1-1/4	22	283.3	4.4	45	70	157 (182)	R 1/8	1.9 (2.1)
32A	R 1-1/2 x 24 x Rc 1-1/2	28	452.1	5.5	52	80	183 (202)	R 1/8	2.7 (3.0)
40A	R 2 x 30 x Rc 2	35	706.5	6.8	65	98	216 (252)	R 1/4	5.1 (6.0)
50A	R 2-1/2 x 38 x Rc 2-1/2	44	1133.5	8.7	77	121	262 (314)	R 1/4	8.4 (9.5)

• The nominal size and the connection size are different.
• The values in parentheses are the values for working pressure 1.6 MPa-2.0 MPa.

AF-5S

Nominal size	Inlet diameter x Throat diameter x Outlet diameter (di x dt x do)	Valve seat diameter	Flow area $\frac{\pi}{4}dt^{2}(mm^{2})$	Lift ℓ (mm)	Dimension L (mm)	Dimension $H_1$ (mm)	Dimension H (mm)	Plug	Weight (kg)
20A	R 1 x 15 x Rc 1	18	176.6	3.3	40	62	163	R 1/8	1.65
25A	R 1-1/4 x 19 x Rc 1-1/4	22	283.3	4.4	47	70	190	R 1/8	2.35
32A	R 1-1/2 x 24 x Rc 1-1/2	28	452.1	5.5	52	79	208	R 1/8	2.90
40A	R 2 x 30 x Rc 2	35	706.5	6.8	65	98	248	R 1/4	5.30
50A	R 2-1/2 x 38 x Rc 2-1/2	44	1133.5	8.7	77	121	315	R 1/4	9.20

• The nominal size and the connection size are different.

Certified Capacity Table for AF-5, 5S

• For steam (saturation temperature) (Pressure vessel structure standard) (kg/h)
• AF-5: 0.1 MPa to 1.6 MPa; AF-5S: 0.1 MPa to 1.0 MPa

| Nominal size \ Pressure MPa | 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 | |---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---| | 20A | 159 | 231 | 310 | 390 | 468 | 545 | 621 | 697 | 773 | 849 | 925 | 1001 | 1076 | 1152 | 1227 | 1303 | 1378 | 1455 | 1531 | 1606 | | 25A | 255 | 370 | 498 | 627 | 751 | 875 | 997 | 1118 | 1240 | 1362 | 1484 | 1606 | 1726 | 1849 | 1968 | 2090 | 2211 | 2335 | 2456 | 2576 | | 32A | 407 | 591 | 794 | 1000 | 1199 | 1396 | 1591 | 1785 | 1979 | 2175 | 2369 | 2562 | 2755 | 2950 | 3142 | 3336 | 3529 | 3726 | 3919 | 4112 | | 40A | 636 | 925 | 1242 | 1563 | 1874 | 2182 | 2487 | 2790 | 3093 | 3398 | 3702 | 4005 | 4306 | 4611 | 4910 | 5213 | 5515 | 5823 | 6125 | 6425 | | 50A | 1021 | 1484 | 1992 | 2508 | 3007 | 3501 | 3991 | 4477 | 4963 | 5453 | 5940 | 6425 | 6909 | 7398 | 7877 | 8364 | 8849 | 9343 | 9826 | 10309 |

• (Boiler structure standard) (kg/h)

| Nominal size \ Pressure MPa | 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 | |---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---| | 20A | 155 | 227 | 299 | 372 | 443 | 515 | 587 | 659 | 729 | 800 | 872 | 942 | 1013 | 1084 | 1156 | 1227 | 1296 | 1367 | 1439 | 1510 | | 25A | 249 | 365 | 480 | 598 | 711 | 827 | 942 | 1057 | 1170 | 1284 | 1398 | 1512 | 1625 | 1740 | 1854 | 1968 | 2080 | 2193 | 2309 | 2422 | | 32A | 398 | 582 | 767 | 954 | 1136 | 1320 | 1503 | 1687 | 1867 | 2050 | 2232 | 2413 | 2594 | 2777 | 2959 | 3141 | 3319 | 3500 | 3685 | 3865 | | 40A | 622 | 910 | 1198 | 1491 | 1775 | 2063 | 2350 | 2636 | 2918 | 3204 | 3488 | 3772 | 4054 | 4340 | 4625 | 4909 | 5187 | 5470 | 5759 | 6041 | | 50A | 998 | 1461 | 1923 | 2393 | 2848 | 3311 | 3770 | 4229 | 4681 | 5140 | 5597 | 6052 | 6505 | 6963 | 7420 | 7876 | 8323 | 8777 | 9239 | 9692 |

• For air (20˚C) (Pressure vessel structure standard) (kg/h)

Nominal size \ Pressure MPa	0.1	0.2	0.3	0.4	0.5	0.6	0.7	0.8	0.9	1.0
20A	257	374	502	630	759	887	1015	1143	1272	1400
25A	413	600	806	1011	1217	1423	1629	1835	2040	2246
32A	659	958	1286	1614	1943	2271	2600	2928	3256	3585
40A	1030	1497	2010	2523	3036	3550	4063	4576	5089	5602
50A	1654	2402	3225	4049	4872	5695	6518	7342	8165	8988

Construction

No.	Part Name	No.	Part Name	No.	Part Name
1	Valve seat	8	Spring plate	15	Hexagon bolt
2	Spring chamber	9	Spring	16	Plug
3	Cover	10	Adjusting screw	17	Hexagon bolt
4	Valve guide	11	Needle valve	18	Seal ball
5	Valve	12	Lock nut	19	Seal wire
6	Retaining Ring C type	13	Split pin	20	Nameplate
7	Spindle	14	Lever	21	Pipe

Operation

(1) Blowout operation As 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 valve commences to blow when the inlet pressure reaches around 3% below the blowout pressure. The fluid starts to leak by simmering and accumulates gradually on the valve holder A. When the fluid pressure reaches the blowout pressure the valve pops.

(2) Closing operation Since the inlet pressure of the safety 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, since the safety valve blows, the pressure of fluid entering into the back of the valve holder (back pressure) adds to the closing force.

(3) Lift lever mechanism

WARNING

1. Do not touch the product/pipes or the lever with bare hands. Failure to follow this notice may result in scalds or injury in case that fluid is hot.
2. When checking the operation of the product, wear earplugs and stand clear of exhaust pipe end during inspection. Do not look down or touch the open end of the exhaust pipe. Failure to follow this notice may result in scalds or injury due to blow-off. Be aware that the product makes a loud noise at start-up.
3. Fluid is discharged from outlet and partly from the other parts.

Due to lift lever mechanism a discharge inspection can be manually performed at more than 75% of the blowout pressure.