MODEL
LOHD
Vent-to-open, spring biased closed, unbalanced poppet logic element with pilot
source from port 1 or 2
SERIES 3 / CAPACITY: 380 L/min. / CAVITY: T-17A
These unbalanced, vent-to-open logic valves are 2-way switching elements that are spring-biased closed and
incorporate an integral shuttle so that the higher of pressures at either port 1 or port 2 can be used as a pilot
source. With port 3 blocked, the valve is held in the closed position by the spring force. With port 3 vented, the
valve will open provided there is sufficient pressure to overcome the spring force. The force generated at port 3,
plus the spring force, must be greater than the sum of the forces acting at port 1 and port 2 for the valve to remain
closed. NOTE: The pilot area (port 3) is 1.8 times the area at port 1 and 2.25 times the area at port 2.
TECHNICAL DATA
Maximum Operating Pressure 350 bar
Maximum Valve Leakage at 110 SUS (24 cSt) 0,7 cc/min.
Pilot Volume Displacement 4,1 cc
Area Ratio, A3 to A1 1.8:1
Area Ratio, A3 to A2 2.25:1
Control Orifice Diameter 0,8 mm
Seal kit - Cartridge Buna: 990-017-007
Seal kit - Cartridge Polyurethane: 990-017-002
Seal kit - Cartridge Viton: 990-017-006
(X)CONTROL
X Not Adjustable
(D)CRACKING PRESSURE
D 50 psi (3,5 bar)
(N)SEAL MATERIAL
N Buna-N
V Viton
MATERIAL/COATING
Standard Material/Coating
/AP Stainless Steel, Passivated
snhy.com/
LOHD
TECHNICAL FEATURES
These valves have positive seals between port 2 and the pilot area.
These valves open quickly when vented. Time to close is difficult to predict as it is dependant on the rate of flow and the pressure drop created as it closes.
Controlling 2 or more of these valves with 1 pilot control is not advised. The shuttle valve creates a flow path between the multiple elements. Using a blocking check
on the pilot of each logic valve will prevent this.
Because these valves are unbalanced, operation is pressure dependent. Opening and closing of the poppet are functions of the force balances on three areas: Port
1 = 100%, Port 2 = 80%, and the Pilot Area = 180%.
Model Code Example: LOHDXDNCONFIGURATION OPTIONS