Relief valve

If the discharge side valve of the pump is left closed, or if the discharge side piping is blocked for any reason while operating the pump, a deadhead operation will occur, which can cause damage to the air chamber, pump, piping, and may lead to fluid leakage. To prevent such deadhead operation, when the pressure inside the piping rises to a certain level, the safety valve releases the fluid to relieve the pressure, thereby preventing accidents in advance.

Notes) Installation position
When returning the liquid to the chemical tank, install the relief valve above the tank. In addition, the outlet side of the relief valve should always be open to the atmosphere. If it is subjected to pressure from the secondary side, the set pressure of the relief valve will decrease.

Back pressure valve

When the differential pressure between the discharge side and the suction side of the pump is low, pulsating flow in the piping can cause overfeeding (excessive discharge). The back pressure valve is a valve that prevents this phenomenon. By applying back pressure to the discharge side, the check ball of the pump closes more securely, and the discharge volume becomes stable.

Anti-siphonage valve

If the pressure on the discharge side of a pump is lower than that on the suction side, the liquid will flow out naturally. This valve is used to prevent such natural outflow.

Valve code explanation

Name	Model	Outside diameter φ(mm)	Max. flow rate (L/min)	Material		Setting pressure range (MPaG)	Installation angle	Connection H: Hose F: Flange (JIS 10K) Rc: Female screw R: Male screw	Applicable pumps	Weight PVC/SUS Approx.(kg)	External dimensions
				Body	Diaphragm
Relief valve Back-pressure valve Anti-siphonage valve	RDN BDN SDN	60	4	PVC _or SUS	FKM _or Hypalon	0.06～0.5	90°	F15A _or F20A	100W・200W・1～130V・3G～350G・Y・4R・1L・2L	1.0 / 3.5	Figure-A
	RD BD SD	80	10					F20A _or F25A	500W・500G・700G・6R・9R・6L	1.4 / 7.0
		100	25					F25A _or F40A	1000W・1500W・14R～22R・9L・13L・17L	2.0 / 10
		120	40					F40A _or F50A	27R・34R・D-32R	3.0 / 16
Relief Valve Back-pressure Valve Anti-siphonage Valve	RDS BDS SDS	60	4			0.06～0.5	180°	F15A _or F20A	100W・200W・1～130V・3G～350G・Y・4R・1L・2L	1.0 / 3.5	Figure-B
		80	7					F20A _or F25A	500W・200G～700G・4R～6R・1L～6L	1.4 / 7.0
Anti-siphonage Valve	SCN	45	1.2			0.06～0.1	90°	Liquid inlet: V _or Pφ4,φ6, U13,F15 Liquid outlet: R3/8・1/2	100W・1～80V・3G～100G・Y	0.4 / –	Figure-C

Notes
1) Setting pressure depend on types: Initial blow-off pressure for Relief Valve, Blow-off pressure for Back-pressure Valve, Shut-off pressure for Anti-siphonage Valve.
2) Ambient temperature: 0 to 40℃, Liquid temperature: 0 to 50℃.
3) Set the pressure respectively for the double head type pumps.
4) Please match the connection diameter with the pump being used. Alternatively, select a product with a diameter equal to or larger than that of the pump.

External dimensions