2-way cartridge valves , pressure limiting function LFA.DBW…E

Description

• Type-examination tested safety valves according to Pressure Equipment Directive 2014/68/EU
• Size 32 … 63
• Component series 7X
• Maximum operating pressure 420 bar
• Maximum flow 5000 l/min
• Size 32 … 63
• Component series 7X

Features

• Installation bore according to ISO 7368 (main pressure relief valve)
• Response pressure 50 to 420 bar
• Additional directional valve connection surface, optional
• adjustment types, optionally:
  - Hexagon
  - Rotary knob
• Valve mounting set (sealable) as accessories

Product description

Type-examination tested safety valves type LFA . DBW…E according to Pressure Equipment Directive 2014/68/EU are pilot-operated 2-way cartridge valves in seat design with set relief pressure setting pmax.

The complete valve generally consists of one cartridge valve (1) for installation bores according to ISO 7368 and one respective control cover (2) with integrated sealed pressure limitation unit (4).

Version “DBW” offers a connection possibility closed by a cover plate (8) for a directional valve with porting pattern according to ISO 4401-03-02-0-05. By attaching a suitable directional valve at the position of the cover plate, an additional function like "depressurized start-up” can be realized. The use of this additional function requires a special set-up of the overall circuitry in order to maintain compatibility with the Pressure Equipment Directive 2014/68/EU.

The factory nozzle fitting (9) (“X”, “F”, “P”) as well as the installed compression spring (10) must not be changed. The installation position (“D”) is not fitted.

The cartridge valve (1) is designed as seat valve without area difference. The relief pressure effective at port A is directed to the spring chamber (6) of the cartridge valve (1) and to the pressure limitation unit (4) via channel X (5). The piston sealing (7) prevents an internal leakage from the spring chamber (6) to port B and thus increases the operational safety by avoiding gap filtration. Under the pressure value set at the pressure limitation unit (4), the spool (3) is pressure-compensated and remains closed in a seat-tight manner due to the spring force of the compression spring (10). The pressure equilibrium at the spool (3) is only changed when the relief pressure at port A is reached, namely by opening the pressure limitation unit (4), so that excessive hydraulic fluid directly flows to channel B via the spool (3) and the pressure in A is limited to the set pressure value.

The pressure limitation unit (4) is optionally available with rotary knob. This allows for a manual reduction of the pressure adjustment without changing the relief pressure setting. This simplifies a regular functional test.

Type code

▢ Information is entered at the factory

Order example:

qV = 2200 l/min, p = 270 bar

→ Type LFA 50 DB.‒7X/270.E

→ TÜV.SV.▢‒1138.48.F.2600.270

Technical data

general

hydraulic

(For applications outside these values, please consult us!)

Diagrams/characteristic curves

Admissible flow ranges – size 32

Mineral oil

(measured with HLP46, ϑOil = 40 ±5 °C)

Other approved hydraulic fluids (see "Technical data")

(simulated; kinetic viscosity 40 mm²/s)

Admissible flow ranges – size 40

Mineral oil

(measured with HLP46, ϑOil = 40 ±5 °C)

Other approved hydraulic fluids (see "Technical data")

(simulated; kinetic viscosity 40 mm²/s)

Admissible flow ranges – size 50

Mineral oil

(measured with HLP46, ϑOil = 40 ±5 °C)

Other approved hydraulic fluids (see "Technical data")

(simulated; kinetic viscosity 40 mm²/s)

Admissible flow ranges – size 63

Mineral oil

(measured with HLP46, ϑOil = 40 ±5 °C)

Other approved hydraulic fluids (see "Technical data")

(simulated; kinetic viscosity 40 mm²/s)

Notes:

• The flow values only apply for depressurized pilot oil return.

• Operating points in the gray areas of the characteristic curves are not admissible with this valve.

• Observe the admissible flows of the overall system.

Symbols/Circuit diagrams

Dimensions

Dimensions in mm

Notice:

The dimensions are nominal dimensions which are subject to tolerances.

Valve mounting set (separate order)

Notices:

• For reasons of stability, exclusively the specified valve mounting screws may be used.

• The specified tightening torques were calculated with total friction coefficient μtotal = 0.09 ... 0.14; adjust in case of modified surfaces.

• The specified tightening torques stated are guidelines when using screws with the specified friction coefficients and when using a manual torque wrench (tolerance ± 10%).

Installation bore and connection dimensions according to ISO 7368 (main pressure relief valve)

Information

Safety instructions

• When selecting a type-examination tested safety valve, it must be observed that for the desired response pressure p the maximum flow possible lies below the admissible flow qVmax . According to the Pressure Equipment Directive 2014/68/EU, the increase in the system pressure due to the flow must not exceed 10 % of the set response pressure (see type key, component marking).

• The maximum admissible flow specified in the component marking qVmax must not be exceeded!

• Discharge lines of safety valves must end in a risk-free manner. Fluid must not accumulate in the discharge system (see data sheet AD2000 A2).

• Safety valves with adjustment type “1” (rotary knob) may only be unloaded in case of maintenance. Operation outside the specified pressure ranges is not admissible.

Always observe application notes:

The response pressure with a flow of 12 l/min and a hydraulic fluid viscosity of 46 mm2/s specified in the component marking is set by default. Within the admissible viscosity range, the response pressure may vary by +3 % (230 mm2/s) to -3 % (12 mm2/s).

• The maximum flow stated in the component marking applies for applications without counter pressure in the control line (port Y).

• By removing the lead seal at the safety valve, the approval according to the Pressure Equipment Directive becomes void.

• The nozzle fittings installed at the factory as well as the main spool compression spring must not be changed.

• Basically, the requirements of the Pressure Equipment Directive and of data sheet AD 2000 A2 have to be observed.

• In order to prevent unauthorized assembly, the valve assembly can be additionally secured by means of the valve mounting set (sealing) (separate order, see “Dimensions”).

Ordering codes

Downloads

2-way cartridge valves, pressure relief function Data Sheet | RE21055 | 2021-02-01 | English, United States | PDF | 631k Product Groups: Control cover Type-examination tested safety valves according to Pressure Equipment Directive 2014/68/EU