Successful but often overlooked Wandfluh Poppet Valve Applications

1.     Refer to data sheet 1.11.2140E.  The typical 3 way, two position control circuits utilize virtual zero leak Wandfluh solenoid operated poppet valves for load lift, hold, and lower functions, but the user still must provide means to dump or shut-off the fixed displacement pump providing pressure and flow. Else, power will be wanted, heat will be generated, and at least 2 more components, plus fittings and piping must be added to the manifold control station.  Wandfluh offers a fourth function as part of the system and housing by also installing another 3 way solenoid valve which (see model A3406 under “Symbols” on page 1)., when signaled can both dump the pump flow to tank and also unload any pressure remaining in the cylinder and piping.  At the rest position (all power to solenoids off), all three ports are locked thus also holding a loaded cylinder in a virtual zero drift position, regardless of any undue forces on the cylinder load. A further benefit is that a “float position is created for cylinder and its load (such as needed by small snowplows or road scrapers.). This model is also offered in the NG4 and NG10 valve sizes.

2.    Refer to data sheet 1.11-2150E. Here we offer a poppet style 4 way 3 position, double solenoid operated directional control valve that will hold all ports virtual zero leak when in the no power (neutral) situation (each port is blocked virtual zero leak.). This is often a requirement in the test bench and fixture clamp markets, as well as on certain positioning loaders/transporters, and in any designed machine that requires both safety when holding a load and fail-safe shut-off of actuators when signaled. 

NEW PRODUCT – Solenoid operated, two way normally closed / normally open shut-off valve that is cavity interchangeable

Wandfluh now offers a solenoid operated, two way normally closed / normally open shut-off valve that is cavity interchangeable with the common U.S. cartridge valve manufacturers’ SC-08-20 screw-in style cartridge with the US standard ¾” -16 UNF Cavity Thread. See data sheet 1.11-2083E. For years this model was used in million quantities by many major US farm and construction equipment manufacturers on tail gate lifts, snow plows, platform lifts, small hydraulic cranes, manlifts, forklifts, pallet stackers and many other applications.  We now receive inquiries from many of our distributors and OEM customers as to its availability from Wandfluh, either to service their customers, or for use in new low flow rate applications where small and virtual zero leak shut-off valves are required, and smaller use quantity orders are asked for and readily available.

In addition to reliable quality and delivery, the Wandfluh model offers higher pressure ratings, and flow rates with some desirable options such as push type manual over ride, mobile equipment type slip-on solenoids offered in a variety of solenoid voltages and electrical connectors, and selection of seal materials.  Free reverse flow when de-energized, virtual zero leak when holding pressure.  Rated to 5000 psi continuous duty at 10GPM (see performance characteristics pg 2). At current known order quantities we cannot match high order quantity pricing, but offer a high quality substitute when this size and type valve is needed in manifolds and systems to enhance performance, or when other sources are not available.

Proportional Solenoid Operated, 3-Way Flow Control Cartridges

New emphasis on more efficient fluid motor driven fan drive systems requires accurate and repeatable proportional solenoid driven 3 way flow control valves, both the direct operated throttle type and the pressure compensated type, this again gives us opportunity for our 3 way screw-in cartridge valves shown in catalog section 2.6. (An example is page 2.6-665E) We can now offer the 3 way direct operated pressure compensated flow control valves, (once termed “Priority Flow Control Valves”) to a variety of mobile equipment manufacturers and users for the control of fluid motor drive circuits that need a high degree of precision and accurate response to feedback signals, over millions of cycles. Our offerings can be fitted with mobile equipment slip-on solenoids, explosion proof solenoids, viton seals, corrosion resistant plating, and other customer requested options, and the necessary electronic amplifiers to control the fan drive system can be supplied with the amplifiers installed in the proportional solenoid, or for external installation.  Valves are offered in 2 sizes, 22mm and 33mm threads, and a 42mm size is now in final design.

For more complete product information see catalog data pages 2.6-666E, 2.6-667E, 2.6-645E, 2.6-646E, and electronic amplifier pages 1.13-75E, 1.13-240E.

2.6 Proportional Throttle Valve, Drop-in Cartridge Style. 42 GPM Flow Rate

For many years Wandfluh has offered a Proportional Throttle Valve in DIN 25 drop-in cartridge style, Model EDR2500-160-G24. It is rated to provide accurate flow rate adjustment from 20 cubic inches per minute to 42 GPM, and pressures to 4500 psi.  This cartridge fits in an ISO 7368/DIN 24342 cavity, or we can provide it installed in a 2-port high strength aluminium housing with either NPT or SAE-16 threaded ports.  This housing model number is K25-100-NPT or SAE  See data page 1.12-505E in the general catalog or online.

This unit uses a 60mm proportional solenoid, available in 12 or 24 VDC, it includes a push type manual over ride, and is enclosed in a flange mount zinc plated steel solenoid housing.  It is available with a selection of electrical connectors including the standard DIN 43650 style.  Stand Wandfluh amplifiers and companion electronics can be used to drive the solenoid. 

The unique Wandfluh pressure balanced metering spool allows a direct solenoid operated design which assures accurate, smooth and fast response to a signal change.  A special data page, 2.6-114 (2 sides) and operating graphs are available on request from the Wandfluh, Mundelein, IL office.

Typical applications for this valve include variable speed control of fluid motor driven conveyors, lowing speed control of weight loaded hydraulic presses, variable speed control of fluid motor driven water pumps and boosters, fluid transfer systems, and mobile equipment fan drive systems.

Ed V. Askey

Accumulator or High Flow Pump Unloading Valve, with Dual Unloading/Reloading Pressure Adjustments

This Unique pressure control valve was developed in Western Europe where power costs are much higher and there is considerably more emphasis placed on efficient hydraulic systems that save power.  Thus, accumulators and high/low pump power units are more often required. Data sheet: 2.1-950E, and 2.1-970E

The main feature of the Wandfluh Accumulator or Pump Unloading Valve is that it offers adjustable pressure control for both the unloading (dump pump flow to Tank) and reloading (rebuild system pressure) functions.  Most unloading valve circuits offer only an unloading pressure adjustment and a fixed not readily adjustable reloading pressure.  The difference between the unloading and reloading pressure is example, typical unload-reload ratio for clamping circuits (hold at high pressure) is 90%; an example would be unload at 1000psi, reload at 900psi, but this is an uncommonly high ratio for many pressure holding circuits, and not practical for fast approach slow feed circuits where there is time to make up stored low pressure volume at low power input, or demand for holding pressure is sporadic and used only for emergencies.  Only one Wandfluh dual Adjustment Unloading valve is required for a wide variety of accumulator pressure control applications, and the desired unload-reload ratio can be re adjusted in the field if unload-reload requirements change.

Other important features are:
1.  Internal spook leakage is extremely low (see page 2 of data page) and thus do net bleed down the charged accumulator quickly and the pressure or charging pump does not have to operate often.
2.  The valve comes in 2 sizes, NG6 (NFPA D03) and NG10 (NFPA d05, and mounts on standard NFPA sub-plates.
3.  The NG6 size can used to pilot larger DIN type poppet vlaves that may require a variety of pilot pressures and flow rates depending on the ratio choices of different sizes of DIN poppet valves. 
4.  Both sizes are rated continuous duty to 5000 psi, peak to 5800 psi. 
5.  All working parts are of steel, sub-plates can be provided in steel or high grade aluminum, pressure adjustment valves have lock nuts; for fine resolution, 3 pressure adjustment ranges are offered as standard, seals are Buna N, or Viton; EP (ethelene propalene) on special quote.
6.  If valves are to be exposed to wet, humid, icy conditions, or salt water, ask us for quotation on CRES surface finishes or Type 316 L stainless steel external parts.

Ed V. Askey

Mini Proportional Pressure Reducing-Relieving Valve Cartridge

Subject:  Data pages 2.3-671E Mini Proportional Pressure Reducing-Relieving Valve Cartridge

New Product Introduction:  Model Number MDPPM16-40-Y-G24-MSA37/19 Direct Acting Proportional Pressure Reducing-Relieving Valve for slip-In-Cartridge cavity.  For low flow rate, lowest pressure adjustment, lowest internal leakage applications.

Ask for data page 2.3-671E on this special application model. We have produced this model for several OEM customers. It is used on pilot control circuits were accurate pressure adjustment is required at very low flow rates and pressure adjustments, and lowest internal leakage is also a critical requirement.

It is rated to accept up to 60 bar (879 psi) input pressure (P port), and adjust downstream (A port) pressure to as low as 1 bar (15 psi) accurately and repeatedly. Internal leakage (past P port) is rated to as low as 30 cc/minute (nominal) with 142 SUS viscosity fluid.

Two pressure adjustments are offered: 1 to 25 bar with the PI29 solenoid, and 1 to 48 bar, with the PI35 solenoid. See pressure operating curves, and dimensions on page 2 of data sheet 2.3-671E. Standard voltages are 12 and 24 volt DC. An explosion proof solenoid model that meets ATEX Standards (Zones 1 & 2) is available on special quotation.

Note: this new cartridge fits an 0.11 mm cavity and a special 3 ported housing for it is available. Ask for Wandfluh cavity drawing 1.1325.4, or ported housing KR-1630-A-S04.

Ed V. Askey

Proportional Solenoid Pilot Operated NG25 (DO8) size Directional Control Valve.

Catalog Section 1.10 – Proportional Solenoid Pilot Operated NG25 (DO8) size Directional Control Valve.

In addition to our cataloged NG3, NG4, NG6, and NG10 solenoid operated spool type proportional directional valves, we also offer a High Flow Rate DO8 (NG25) size proportional solenoid operated contol valve to authorized distributors.   See data page on model AVPWS4D251-250-ti-G24-HB4.5. 

We continue to ship more of these every month, and have reordered the main valve sections from Nachi, due to increasing demand.  These DO8 sized valves were offered by Wandfluh many years ago, but removed from the line when the main spool body castings became unavailable in Switzerland.  Upon increasing requests, we developed an agreement with Nachi US to supply us the body sections with proportional fit spools, and adapted our standard proportional pressure control sandwiches to pilot them.  Our net price to an authorized  distributor is among the best on the market for a DO8 size (NG25) proportional directional control valve, double solenoid, 4 way 3 position, 24 VDC, closed center or motor spool.  These valves are rated to 66 GPM and 250 bar, and we have excellent performance reports from the field.  Standard Wandfluh Electronics drive these valves.

These valves can readily be supplied with the EEx me ll explosion proof, ATEX rated, European Norm solenoids, now becoming accepted worldwide (though not yet with UL/CSA approvals).  The pilot sandwich shown (model AEPSVdAB6-G24-0.6) would simply be replaced with a model BDPCS-AB-20-0.6-G24/T4- (see data sheet 2.3.740E) shown in the newest volume 13 and up catalogs.  Best of all, delivery is excellent!

If you’re interested, Bill Smith can work up a quote for you based on the net price sheet with the explosion proof solenoids on the NG6 pilot pressure control sandwich. 

Ed Askey

Proportional Flow Control Valve, Direct Operated, Pressure Complensated, full range adjustableto 16.6 GPM and rated to 5000 PSI working pressure

New Product, Models QNPF-A10-A/B-63-G24, and QNPS-A10-P-63-G24.  NG10 (NFPA 05) Sub-Plate Mount or Sandwich Mount styles.  See new data page 2.6-860E , now on our website.  This new data page will be included in the next printing of our bound catalog.

These units feature the proven QNPPM33-63-G12/G24 Screw-In threaded Cartridge, which allows higher flow rates and working pressures,  installed in steel sub-plate or sandwich mount housings.  See data page 2.6-650E for complete operating detail.  Also available with Integrated Electronics installed in the Solenoid Housing  (DSV Smart Valve).  See data page 2.6-660E.

These units supercede the previous model series AEMR-N or P- 10/2-40-G12/G24, a long time Wandfluh proportional flow control valve rated to 10.4 GPM and 3650 psi, which will remain available to support the large number of units now in the field, but we recommend installing the new units on neo generation designs, and wherever there is no problem in adapting existing design inputs to new flow rate/pressure ranges.  Also, the new style valves are priced lower than the older style.

Other advantages of the new screw-in cartridge design are:  faster and easier installation or removal of the screw-in cartridge, zinc plated steel solenoid housing for better corrosion resistance, common M33x2 metric cavity will accept a throttle valve version rather than pressure compensated version if required, or the SVS/X33 series of 2 way poppet type shut-off or dump valves.  This simplifies inventory requirements, and circuit installation procedures where all three types of valves may be required.

Ed V. Askey

Stand Alone DSV Amplifier, mounts separately from Proportional Valve Solenoid, Meets IP67 International Protection Standards. Basic Model number is DSV3202-D20-AA

Wandfluh of America offers a separate (sealed) Digital Smart Valve amplifier that encloses the card used in the DSV Integral Electronics, and the New SD62 series (replaces the obsolete SO5V Din Rail mount series). This was developed for several major OEMs that could not use the DSV integral electronics models, and required amplifiers that provided protection against severe ambient such as wind, rain, snow storms, salt spray, etc., and meet IP67 Internationa Protection Standards.  We are in full production now on several models, and the field response had been excellent!

The DSV Standalone offers all the performance options of the SD62 series, and can easily be installed and adjusted with an IBM compatible PC, and a set of inexpensive cable connections.  A free PASO installation program can be down loaded from the Wandfluh Website (  On request the unit can be programmed before shipment for a minimal fee.

The exact IP67 International Protection Standard requires protection against ingress of dust, complete protection against contact, and protection against water when the enclosure is totally immersed under defined conditions of pressure and time. Other advantages are:

  • Accepts either voltage or current adjustable preset values (command input)
  • Adjustable Ramps for both up and down, adjustable gain, offset, and inversion
  • Five different operation modes (i.e. uni-polar 1or 2 solenoid, bi-polar 1 or 2 solenoid
  • Uni-polar control 2 concurrent solenoid functions
  • Adjustable Dither, both frequency and amplitude
  • Adjustable Dead Band

For additional information on these functions, and technical data, refer to the SD62 data sheets 1.13-100E, or the SD62 Operating Instructions (can be downloaded from the internet). Also, refer to the DSV data sheets 1.13-50109E.

As you can see, there are many options and functions available so currently we request that you discuss your applications for this new product with us, and we will then present you with model numbering and net distributor pricing.

Ed V. Askey

Wandfluh Pilot Operated Check Valve, Screw-in Cartridge Style

See Section 2.7, Data Pages 2.7-62E  Model RNX-PM33-x. This model is also still available in the smaller 22mm size, though it is not in the latest catalog. Design features are the same, parts are scaled down.

The design offers some desirable features that assure superior operating performance in the critical load holding area as well as providing long wearing reliable product so important in heavy duty mobile equipment machines.

1.  Note the poppet type spool is push type to seal and held in position by both the pilot spring and the actuator pressure; thus insuring that the tapered poppet/spool is fully seated and driving the poppet onto the seat.  This adds additional strength to the holding force, and aids in forming a tighter seat to assure virtual zero leak when holding a loaded cylinder.

2.  Note also that the pilot spool is fully guided (bearing) and the poppet seat cannot cock or the seat, or wobble when traveling.

3.  Note that there is a O ring groove cut in the pilot piston. This allows for an O ring seal on the pilot piston when the pilot piston can receive the signal for pilot shift function if pilot pressure is used from another separate function. For ordering this option, signify b adding the number C7 to the end of the model number.

4.  All steel metal parts, such as the one piece cartridge body, are of zinc plated steel, (stainless on special option) and are rated to 5500 psi continuous duty. Standard seals are of Buna N (Nitrile) Rubber, or Viton, ethylene propylene (EPR) seals on request.

5.  The model RNXPM33-x is rated to 350 bar working pressure, 160 liters/minute. The model RNXPM33-x is rated to 350 bar and 80 liters/Minute. 

Ed V. Askey