Yoshitake AL-280 relief valve is a closed type relief valve exclusive for the pressure control of pumps with high pulsation pressure or large pressure fluctuation. The trim parts (valve and valve seat) feature a dashpot structure designed to continuously discharge liquid against its setting pressure change without popping, preventing the relief valve from chattering and hunting. Stainless steel with excellent corrosion resistance is used for the adjusting spring.

Specifications

Structure	Closed type
Application	Cold and hot water, Oil (heavy oil A, heavy oil B, kerosene), Non dangerous fluid (Less than 20 cst)
Working pressure	0.05-1.0 MPa
Working temperature	5~120°C
Material	Spring case: Ductile cast iron Valve, valve seat: Stainless steel Adjusting spring: Stainless steel
Connection	JIS 10K FF flanged

INFO

Please refer to the flow rate charts for set pressure range.

Dimensions and Weights

Nominal Size	L	H	H1	D	C	t	n-h	Weight (kg)
15A	90	245	108	95	70	18	4-15	4.7
20A	90	245	108	100	75	18	4-15	5.0
25A	90	245	108	125	90	18	4-19	6.2
32A	91	285	115	135	100	20	4-19	8.6
40A	91	285	115	140	105	20	4-19	8.8
50A	105	331	132	155	120	20	4-19	13.0

Dashpot Structure

Parts and Materials

No	Name of Parts	Material
1	Body	Ductile Cast Iron (FCD450)
2	Spring Case	Ductile Cast Iron (FCD450)
3	Valve Seat	Stainless Steel (SUS304)
4	Valve	Stainless Steel (SUS304)
5	Spindle	Brass (C3604)
6	Spring	Stainless Steel (SUS304)
7	Lower Spring Plate	Brass (C3604)
8	Upper Spring Plate	Brass (C3604)
9	Adjusting Screw	Brass (C3604)
10	Lock Nut	Brass (C3604)
11	Cap	Cast Iron (FC200)
12	Gasket	Non-Asbestos
13	Gasket	Non-Asbestos
14	Stud Bolt	Rolled Steel (SS400)
15	Nut	Rolled Steel (SS400)
16	Name Plate	Stainless Steel (SUS304)
17	Rivet	Carbon Steel (S15C)

Flow Rate Chart

The flow rate to each nominal size when the accumulation (overpressure to the set pressure) is 25% is as shown in Fig. 1. See Fig. 2 when the accumulation is less than 25%.

Fig. 1: Nominal size selection chart

Fig. 2: Approximate flow rate magnification

When the accumulation is less than 25%, select an approximate flow rate magnification matching the accumulation based on this chart, and multiply the flow rate at 25% accumulation by the selected magnification.

Examples

Example 1: Nominal Size Selection To select a nominal size when the working conditions are pressure: 0.3 MPa and discharge capacity: 1.0 m³/h, first find intersection point A of the pressure of 0.3 MPa on the horizontal axis and the discharge capacity of 1.0 m³/h on the vertical axis in Fig. 1. Since intersection point A lies between the curve of nominal sizes 15A·20A and the curve of nominal size 25A, select the larger one, 25A.

Example 2: Flow Rate Calculation To obtain the flow rate when the working conditions are nominal size: 25A, setting pressure: 0.1 MPa, and accumulation: 20%, first find the flow rate at an accumulation of 25% in Fig. 1. Then, mark intersection point B of the accumulation of 20% and the diagonal straight line in Fig. 2. Trace horizontally to the left from this intersection point B, and reach the point of 0.8 on the axis of approximate flow rate magnification.

Discharge Capacity (Reference) at 25% Accumulation

Flow rate is given in m³/h.

Nominal size	Flow area (mm²)	0.05 MPa	0.1 MPa	0.2 MPa	0.3 MPa	0.4 MPa	0.5 MPa	0.6 MPa	0.7 MPa	0.8 MPa	0.9 MPa	1.0 MPa
15A·20A	16.7	0.20	0.29	0.41	0.51	0.59	0.66	0.72	0.78	0.83	0.88	0.93
25A	39.2	0.49	0.69	0.98	1.20	1.38	1.54	1.69	1.83	1.96	2.07	2.19
32A	91.9	1.14	1.62	2.29	2.81	3.24	3.63	3.97	4.29	4.59	4.87	5.13
40A	143.6	1.79	2.53	3.58	4.39	5.07	5.67	6.21	6.71	7.17	7.61	8.02
50A	224.3	2.80	3.96	5.60	6.86	7.92	8.86	9.71	10.49	11.21	11.89	12.53

Relief Valve Discharge Piping

Select a pipe with a same or larger diameter than the outlet diameter of the valve.