Pressure Ratings for Lee Precision Microhydraulic Products

The restrictors and valves manufactured by The Lee Company may be classified by their "maximum working pressure differential" into four broad categories of 3,000, 4,000, 5,000, and 8,000 psi. These categories correspond generally to the common system pressures in use today.

Many applications do not expose the Lee Insert to the full system pressure differential. In such cases it may be possible for the designer to safely specify a Lee component with a lower working pressure differential than the system pressure. Our staff of sales engineers is ready to help you select the proper Lee Insert for your application.

Government/Industry Standards

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FOR COMPONENTS (psi)
MIL-H-5440H
MIL-H-8891A
Nominal
System
Pressure
3000 4000 5000 8000
System
Peak
Pressure
4050 5400 6750 9600
Proof
Pressure
4500 6000 7500 12 000
Burst
Pressure
7500 10 000 12 500 16 000

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FOR LINES, FITTINGS, HOSES and COUPLINGS (psi)
MIL-H-5440H
MIL-H-8891A
Nominal
System
Pressure
3000 4000 5000 8000
System
Peak
Pressure
4050 5400 6750 9600
Proof
Pressure
6000 8000 10 000 16 000
Burst
Pressure
12 000 16 000 20 000 24 000

† Lee Plugs should be selected to meet these requirements.

Restrictors

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PRODUCT MAXIMUM WORKING PRESSURE (psid)
3000 4000 5000 8000
JETA      
JEHA      
JEKA      
JEBA      
VXCA      
JEVA      
VDCA      
JHTA      
JHHA     * **
JHBA      
VHCA      

*Continuous      **Intermittent

Lee Company Restrictors are designed to withstand transient pressure surges higher than the maximum working pressure differential. Continuous flow with low downstream pressure may cause cavitation, and should be avoided. Click here for more information on cavitation.

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Max. Working
Pressure (psid)
3000 4000 5000 8000
System Peak
Pressure (psi)
4050 5400 6750 9600

Conventional hydrostatic proof and burst pressure testing applies equal pressure to all parts of a Lee restrictor. The Lee insert is therefore unaffected. Maximum hydrostatic pressure in this condition is limited only by the strength of the housing into which the Lee insert is installed.

Lee Chek and Relief Valves

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PRODUCT NOMINAL SYSTEM PRESSURE (psi)
3000 4000 5000 8000
CK 187 (Axial)      
CK 250 (Axial)      
CK 187 (Side Exit)      
CH 343 (Side Exit)      
CS 187      
CS 250 (Zero Leak)      
CK 187 Lo-Lohm   ††    
CK 250 Lo-Lohm      
CK 375 Lo-Lohm      
CK 500 Lo-Lohm      
CK 500 (Hi-Q)      
CK 750 (Hi-Q)      
CK 1000 (Hi-Q)      
CH 125      
CH 156      
CH 187      
CH 250      
CH 375      
CH 500      
CP 250      
RC 187      
PR 187      
PR 281      
PR 375      
PR 500      
PH 281      
PHR 375      
PRT 187      
PHT 250      

† Flow rate limited.
†† Flow rate limited for screened, forward flow versions.

These Lee Company check valve and relief valve products are rated for continuous system pressures in both the checked and flow directions. Relief valves are typically closed against system pressure and will be called upon to open on occasion and to flow at pressure differentials up to the system peak pressure.

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Nominal System
Pressure (psi)
3000* 4000* 5000 8000
System Peak
Pressure (psi max.)
4050* 5400* 6750 9600

* See table above for exceptions.

With pressure applied in the flowing direction, conventional hydrostatic proof and burst pressure testing applies equal pressure to all parts of a Lee chek valve; and in the case of a pressure relief valve, a pressure differential equal to the cracking pressure will result. The Lee chek or relief valve is therefore unaffected. Maximum hydrostatic pressure in this condition is limited only by the strength of the housing into which the Lee valve is installed.

A hydrostatic test for proof or burst pressure applied in the opposite direction (i.e. the checked direction) will stress the Lee chek or pressure relief valve.

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Nominal System
Pressure (psi)
3 000 4000 5000 8000
Proof Pressure in
Checked Direction
(psi)
6 000 7 000 7 500 12 000
Burst Pressure in
Checked Direction
(psi)
10 000 11 000 12 500 16 000

Standard Shuttle Valves and Flow Control Valves

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PRODUCT NOMINAL SYSTEM PRESSURE (psi)
3000 4000 5000 8000
SV 187 / SH 187   *  
SV 281 / SH 281   *  
SV 500 / SH 500   *  
FC 187      
FC 281      
FC 375 / FH 325    
FC 500 / FH 500    
FL 281      
FL 500      

* Flow rate limited (see Shuttle Valves).

Lee Company Shuttle Valves have the same continuous system pressure rating for both normal and emergency modes
of operation.

Lee Company Flow Control Valves have the same continuous system pressure rating for both the metered flow and the free flow directions. Continuous flow with low downstream pressure may cause cavitation, and should be avoided. Click here for more information on cavitation.

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Nominal System
Pressure (psi)
3000 4000 5000 8000
System Peak
Pressure (psi max.)
4050 5400 6750 9600

For Lee Company Shuttle Valves, a hydrostatic test for proof or burst pressure applied at either the normal or emergency port (with the cylinder port capped) will stress the valve. Proof and burst ratings are the same for both cases.

For Lee Flow Control Valves, conventional hydrostatic proof and burst pressure testing applies equal pressure to all parts of a flow control insert. The Lee insert is therefore unaffected. Maximum hydrostatic pressure in this condition is limited only by the strength of the housing into which the Lee insert is installed.

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Nominal System
Pressure (psi)
3 000 4000 5000 8000
Proof Pressure (psi) 6 000 7 000 7 500 12 000
Burst Pressure (psi) 10 000 11 000 12 500 16 000

Standard Line Mounts

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PRODUCT MAXIMUM WORKING PRESSURE (psid)
3000 4000 5000 8000
Style "B"
AS4395 Ends

     
Style "C"
AS4375 Ends
       
Style "E"
AS4395 Ends

     
Style "F"
AS4375 Ends

     
Style "G"
AS85720/1 Ends
     
Style "H"
AS85720/1 Ends
     
Ring Locked
Adapters
   
VXLA      
VDLA      

The maximum working pressure differential, and the transient surge pressure of the fitting, is limited by, and is a function of, the Lee insert that is installed in the fitting.

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Max. Working
Pressure (psid)
3 000 4 000 5 000 8 000
Proof Pressure (psi) 6 000 8 000 10 000 16 000
Burst Pressure (psi) 12 000 16 000 20 000 24 000

 

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