Lee Restrictor Primer
Lee Jets are the simplest, most accurate, most economical jets ever developed! You simply insert Lee Jets into reamed holes and lock and seal them by pressing the pin into the body. You specify either the flow and pressure drop or use the Lohm system. Lee Jets do the rest. Quick, easy installation eliminates costly assemblies, seals, threads, flow testing and filter design. The Lee Company 100% flow tests all Lee Jets to two standard tolerances, ±2% and ±5%.
Each Lee Jet unit contains a calibrated orifice, two matched safety screens so you can flow in both directions, and the reliable locking and sealing device adapted from Lee Plugs, which have been accepted for years as the best way to seal drilled holes.
Lee Jets are available from stock in a wide range of 53 Lohm ratings from 800 to 30,000 Lohms. Lee Jets improve your design saving time, space and money.
HIGH WATT and KILOWATT JETS
Lee High Watt and Kilowatt Jets provide accurate, screened, bidirectional metered flow in the 90-1000 Lohm range. The integral screens are machined and drilled from bar stock for maximum strength and erosion resistance. Due to their rugged construction, they can readily withstand the high power dissipation that is often associated with low Lohm applications. For instance, a 200 Lohm JEHA1875200L dissipates 9.6 horsepower, or 7.1 kilowatts, at 3000 psi differential. Use these strong High Watt and Kilowatt Jets for all low Lohm (high flow) applications. Lee High Watt Jets are available in ±2% and ±5% tolerances and Kilowatt Jets in a ±5% Lohm rate tolerance.
Lee Microjets are precision calibrated orifices designed for flow balancing in liquid cooling applications where system pressures are below 500 psid. Lohm rates range from 475 to 3100 Lohms and Microjets are 100% flow tested to a ±2% tolerance, unidirectionally. Lee Microjets are protected in the flow direction by an integral safety screen and are also easily installed and extracted, facilitating easy flow balancing.
Lee Microjets are easily installed into heat exchanger return ports. Their small size allows them to be located directly behind quick disconnect fittings.
The Lee Bender Jets incorporate multiple orifices in series, with successive orifices on the centerline and displaced from it, to force fluid to “bend” as it passes through the unit. The combined effect is an increase in the orifice size for a given Lohm rate. The orifices are bigger than a single orifice, but not as large as the passageways in a Lee Visco Jet. All units are protected with two integral safety screens for bi-directional flow, and are available calibrated to a ±5% tolerance in the 1900 to 9500 Lohm range.
AXIAL VISCO JETS
The Lee Axial Visco Jet also uses multiple orifices in series, but uses spinning to increase Lohm rate. Spinner discs alternately reverse the direction of spin of the fluid. The result is a larger passage size than a Bender Jet for a given Lohm rate but smaller than a Visco Jet. Rugged screens protect the orifice in both flow directions. Axial Visco Jets are available calibrated to a ±5% tolerance in the 680 to 11,000 Lohm range.
Lee Visco Jets come in two insert versions (18-Series and the JEVA) and 3 cartridge sizes (43-Series, 68-Series and the 14-Series). The 18-Series Visco Jet is an insert with 12 different Lohm rates from 11,200 to 313,000 Lohms. The JEVA is a radically new version of the 18-Series Visco Jet. It incorporates vastly increased
minimum passage sizes for corresponding Lohm rates: up to 90% increase over some existing 18-Series units. In addition, 93 Lohm rates completely cover an extended range from 3520 to 313,000 Lohms.
The 43-Series, 68-Series and 14-Series Visco Jets are cartridge mount units that offer the largest minimum passage for a given Lohm rate as well as the highest Lohm rates available. For instance, a 4000 Lohm 14-Series Visco has a minimum passage of 0.055 inch. A 4000 Lohm single orifice would be about 0.012 inch in diameter. One of the 43-Series Viscos offers a Lohm rate of 2,200,000 Lohms, with a 0.005 inch minimum passage, the equivalent of a 0.0006 inch diameter single orifice.
All Lee Visco Jets are available calibrated to a ±5% or ±10% tolerance. Visco Jets with minimum passageways of 0.032 inch or less are protected with two safety screens for bi-directional flow applications.
THE PRINCIPLE BEHIND THE UNIQUE LEE VISCO JET PERFORMANCE
The Visco Jet consists basically of three discs mounted one upon the other to form an extremely complex fluid passage. Fluid enters at the center of one disc and passes through a slot which is tangential to a spin chamber. This discharges through a small center hole into an other chamber. This process repeats over and over. Since the spinning liquid makes many revolutions in each spin chamber, the resulting fluid resistance uses the flow passage surfaces many times. The tangential nature of the slots overcomes sensitivity to viscosity. The centrifugal force of the liquid maintains a back pressure on the discharge of the slot which is proportional to the square of the RPM of the spinning liquid.
This provides a reasonable degree of viscosity compensation without the use of any moving parts.
Some Lee Visco Jets are made from solid stainless steel discs, while others are fabricated from photo-etched stainless steel plates which are bonded together to produce a homogeneous leak-proof product. All Visco elements are rigidly and permanently retained in their respective inserts, cartridges, or linemounts. Standard Lee Visco Jets are calibrated to the noted Lohm ratings in both directions.
There are always some particles of dirt or metal or lint in any hydraulic system even after it has been cleaned and filtered. Sometimes the hydraulic equipment actually generates these particles due to moving parts and there are always many more small particles than there are large ones. The size and number of these particles limit the orifice size which can be used for fluid restrictors. If a small orifice clogs, it usually means failure of a complete system.
The use of the Lee Visco Jet enables you to use much larger passages and still obtain the same amount of restriction which your system demands. Since the minimum passageways in the Lee Visco Jet are larger than for an ordinary orifice, it also means that the hole size in protecting screens may be made proportionately larger. With both larger passageways and larger screen hole sizes, your system will tolerate a much higher level of contamination. Any particle which will pass through the screens, which we use to protect our Visco Jets, will also pass right through the Visco Jet without causing any blockage or build-up of fluid restriction. Now you can use the fluid resistance values you need without fear of system failure due to contamination.
LOHMS VERSUS HOLE SIZE
An example of this is shown by a Visco Jet having 0.015 inch diameter holes and flowing at the same Lohm rate (32,600 Lohms) as the Standard Lee Jet having 0.0048 inch hole size. Thus the same Lohm rate can be obtained with 3.1 times the hole diameter and over 9 times the hole area!
TO PREVENT CLOGGING, YOU NEED LARGER HOLES - Compare these values: