Frequently Asked Questions
General
Q: Will PacSeal Hydraulics ship internationally?
A: Absolutely. While we have global distributors, we will certainly accept orders from customers in all corners of the world when terms and conditions have been met. This is typically done through your freight forwarder.
Q: What hydraulic fluid do you recommend?
A: The hydraulic fluid to be used depends on the application, temperature range (maximum and minimum expected operating temperature), and environmental regulations that may require water-based fluids. PacSeal’s hydraulic control components will work with virtually any working fluid. However, for water-based hydraulic fluids (e.g. water glycol) special alloy seal rings may be required to withstand the higher wear caused by reduced lubricity. Water-based hydraulic fluids generally have a significantly lower viscosity grade (lubricity) in comparison with synthetic or conventional hydraulic oils. This reduction in viscosity/lubricity will cause higher wear and potentially galling on the sealing components, which will reduce the service life dramatically. This is true for any hydraulic valve on the market. Contact us today to determine the right solution for your application.
Q: What are the fluid cleanliness requirements for SV Directional Control Valves and KR Pressure Regulators?
A: The SV and KR valves are ShearFlo® sealing products, which are some of the most contamination resistant fluid power control components in the world. Thus, any other component in your hydraulic control system will more than likely have a fluid cleanliness requirement that will exceed that of the SV and KR valves. Because the sensitivity for these ShearFlo® products is low to average, a good guideline to follow is the ISO code numbers 20/18/15. Please note that any valves that remotely pilot the SV or KR valves should have a much stricter fluid cleanliness requirement. So, it may be a good idea to have a separate fluid source with finer filtering for solenoid cartridge or spool type valves that are used for piloting the actuator on an SV or KR.
SV Directional Control Valves
Q: Can I order repair kits for my SV Directional Control Valve?
A: Yes. Please see SV Valve Accessories and Repair Kits and scroll to find O-ring, Seal, Minor Repair, or Major Repair Kits for your specific valve.
Q: Are PacSeal SV Repair Kits compatible with Barksdale Shear-Seal Valves?
A: Most models are interchangeable with other brands. Please contact PacSeal Hydraulics with your model and size and we will direct you to the correct Repair Kit for replacement.
Q: Why are there special repair kits for the SV-50 Spring Centered Valves?
A: To return to center, the actuator’s torsion spring must have great enough stiffness to overcome the shift force of the valve under pressure; thus increasing the overall shift force from center to clockwise or counterclockwise. To reduce the overall shifting force of the valve, special low load seal rings and accompanying body are used for high pressure applications and for the spring centered model. When requesting a repair kit for your spring centered valve, please provide the serial number of the valve, and/or the year it was purchased, and/or the original sales order/purchase order number used.
Q: Are PacSeal Hydraulics’ Valves 100% made in the USA?
A: Yes! From sourcing raw material to shipment, all manufacturing and production takes place in Southern California.
Q: What is the Cv value for the valves?
A: Cv is the valve sizing flow coefficient that is determined experimentally for each size and style of a valve with water at standard operating conditions. Thus, a valve’s Cv can be expressed as the number of gallons of water per minute (GPM) at 60°F that can flow through the valve in one minute with a difference in pressure across the valve as one pound per square inch (psi). Cv is directly proportional to the valve’s flow rate (Q) and specific gravity (SG) of the fluid but inversely proportional to the pressure drop DP, which can further be expressed by the following equation:
This coefficient increases with the size of the SV Directional Control Valve and dictates the pressure drop across the valve given the system’s supply flow rate. See definitions of other industry terms in our Glossary.
Q: Can the SV manual handle be re-oriented?
A: Yes. The handle can be rotated 180° by removing the shaft nut and washer. For a smaller footprint handle that accommodates right and left-handed users, try our OEM Wing Handle that may be ordered as a spare part.
Q: Can actuator cylinders be installed on an existing valve?
A: Yes. Retrofitting is simple and can be done so by purchasing an actuator cylinder with a bracket kit. Please see the valve’s maintenance instructions for appropriate disassembly and assembly instructions.
Q: Can SVX integral actuators be installed on an existing valve?
A: No. To create the most efficient and reliable actuator and valve assembly, the shaft and housing are unique for this combination. Please call us today for further guidance.
Q: Why does PacSeal’s Selector valve match the same valve schematic as the Fluid Power Industry’s All Blocked valve?
A: In BOP (Blowout Preventer) control systems, “selector” valve is the common nomenclature for a valve with all ports blocked in the center position while venting the case of the valve to the return line. On the other hand, PacSeal’s “All Blocked” valve has all ports blocked (including the return line) in the center position – thus requiring case drain from the housing, which requires additional porting. This allows the return port to be pressurized in the All-Blocked valve (whereas the Selector cannot). NOTE – The pressure on the All-Blocked return and case drain port cannot exceed 250 psi during shifting.
This All-Blocked valve is typically used in subsea ROV applications, which is in PacSeal’s SVS Valve, special hydraulic test unit applications, etc. Note that this valve configuration is more expensive and is not readily available, so we will always recommend a “selector” for most applications that do not need a pressurized return port.
Q: Does PacSeal offer a “motor spool” valve option?
A: Yes. In BOP (Blowout Preventer) control units, a “manipulator” valve is synonymous with the “motor spool” valve that is commonly used in the fluid power industry. Thus, when requesting a motor spool directional control valve ensure to specify a “manipulator” valve.
Q: Will PacSeal’s SV directional control valves be a functional replacement for Snap-Tite Direc-Trol valves?
A: Yes. Our SV product line matches the same porting size, flow rate, pressure rating, and function as the Snap-Tite Direc-Trol valves. Both valves are categorized as “shear-type” with high cycle life, contamination resistance, zero/miniscule internal leakage, etc. as discussed on our page ShearFlo® Features. When replacing your Snap-Tite Direc-Trol valve with a PacSeal SV directional control valve, keep in mind that SnapTite’s flow pattern names vary as follows: Closed Center (Snap-Tite) = Selector (PacSeal), Tandem Center (Snap-Tite) = Manipulator (PacSeal), and Float Center (Snap-Tite) = Open Center (PacSeal). Additionally, the manifold mounting pattern is slightly different between Snap-Tite and PacSeal valves so conversion subplates or a new manifold will be required. Contact us today to assist you in converting your hydraulic control system.
Q: Will PacSeal’s SV directional control valves be a functional replacement for Parker Teledyne Republic Manatrol valves?
A: Yes. Our SV product line matches the porting size, flow rate, pressure rating, and function as the Parker Teledyne Republic Manatrol “Lo-Torq” directional control valve series. Both valves are categorized as “shear-type” with high cycle life, contamination resistance, zero/miniscule internal leakage, etc. as discussed on our page ShearFlo® Features. When replacing your Teledyne Republic Manatrol manual selector valve, note that the 8000E, 8100E, and 8500 series valves may be functionally replaced with any SV valve size. Additionally, the 8400E “Mini Selector” valves may be functionally replaced with PacSeal’s SV-12. Note that the manifold mounting pattern is slightly different between Teledyne and PacSeal valves so conversion subplates or a new manifold will be required. Contact us today to assist you in converting your hydraulic control system.
Q: Why is the grease zerk fitting leaking?
A: This can be caused by multiple things, but the main reason we’ve seen this happen is a faulty grease zerk. However, before you request replacements, please check the following two conditions: (1) is the grease zerk pointing upwards? If it’s pointing downward, then either flip the valve 180° or install an 1/8 NPT plug in its place. (2) Is there back pressure from the return port? The housing is rated to 250 psi, so if the housing internal pressure exceeds this value, then the grease zerk will leak. The grease zerk is supplied in the case that the valve will be in storage for long-term. If the valve is put to use within a few months, then it may be best to replace the leaky grease zerk with an 1/8 NPT plug. If a grease zerk is absolutely desired, then please reach out and we will send replacements promptly. Please note that there is nothing to be concerned about and that this is a very simple fix.
Q: Why is my SV valve leaking after BOP FAT?
A: BOP FAT requirements are to pressurize the control system to 4500 psi. While a 3000 psi SV-100 or SV-150 ShearFlo® seal valve can hold pressure at 4500 psi, the valve must not be shifted. Shifting a valve above its maximum rating will destroy the seal rings and rotor. If you would like to have a valve that can function up to 6000 psi, then please submit a quote for an SV-100/6k or SV-150/6k. Please note that this cannot be retrofitted in the field.
Q: Why are SV valves considered zero leak when they have a leak rate of 0-1 drip/minute?
A: One of the criteria of our factory acceptance tests is 0-1 drip/minute. Although the majority of the valves that leave our facility have 0 drips. A drip may be caused by a small blemish on the seal ring or rotor, which is not a concern. While leaking hydraulic fluid should always be a concern, please keep in mind that one drip/minute equates to only about one gallon in four months. This usually is unnoticed when compared to the greater leak rates of various pipe fittings, ball valves, etc. found in a control system.
Q: What is interflow?
A: Interflow is fluid that is relieved from the pressure and cylinder ports within the valve body/housing during shifting/actuation. Interflow may cause a slight pressure decrease in the control system. The amount of pressure decrease depends on how slow/fast the actuation is made as well as the size of the valve. The slower the shift and larger the valve, the greater the amount of interflow and pressure decrease in the control system. The advantage is that interflow lubricates the valve and enhances longevity. For applications where a pressure decrease is unacceptable, a non-interflow valve option should be sought. The difference is the surface area of the seal ring seat that makes contact with the rotor. Non-interflow seal rings have a very large seat that covers the rotor ports during shifting. However, greater surface area means greater friction, which translates to a higher actuation torque rating. We currently offer a non-interflow option for the SV-25 directional control valve, which has proven itself in various applications. However, if you are interested in a non-interflow option in any of our other valve sizes, then please reach out and we will work up a custom design for you.
KR Pressure Regulators
Please read our KR Pressure Regulator system integration guidelines, operation, and troubleshooting page before installation and troubleshooting.
Q: Can I order repair kits for my KR Pressure Regulator?
A: Yes. Please see KR Pressure Regulator Accessories and Repair Kits and scroll to find O-ring, Seal, Minor Repair, or Major Repair Kits for your specific regulator.
Q: Are PacSeal KR Repair Kits compatible with Barksdale Shear-Seal Pressure Regulators?
A: Most models are interchangeable with other brands (i.e. Barksdale, Gilmore, DTL, etc.). Please contact PacSeal Hydraulics with your model and size and we will direct you to the correct Repair Kit for replacement.
Q: Are PacSeal Hydraulics’ Pressure Regulators 100% made in the USA?
A: Yes! From raw material to shipment, all manufacturing and production takes place in Southern California.
Q: What is the Cv value for the pressure regulators?
A: Cv is the valve sizing flow coefficient that is determined experimentally for each size and style of a valve with water at standard operating conditions. Thus, a valve’s Cv can be expressed as the number of gallons of water per minute (GPM) at 60°F that can flow through the valve in one minute with a difference in pressure across the valve as one pound per square inch (psi). Cv is directly proportional to the valve’s flow rate (Q) and specific gravity (SG) of the fluid but inversely proportional to the pressure drop DP, which can further be expressed by the following equation:
This coefficient increases with the size of the KR Pressure Regulator and dictates the pressure drop across the regulator given the system’s supply flow rate. See definitions of other industry terms in our Glossary.
Q: Why won’t my KR Pressure Regulator adjust to a new pressure?
A: When the set pressure on a spring operator is being changed or adjusted, the outlet needs to be briefly opened and closed a few times to allow the operator and pressure to stabilize. This can be achieved by operating a (downstream) manifold control valve or installing a separate, much smaller valve directly on the outlet line near the KR. The control valve should be briefly opened and closed (one to three times) after the KR has been adjusted; this will stabilize the pressure reading.
Q: How do I improve my KR Pressure Regulator’s adjustment sensitivity?
A: The adjustment sensitivity is related to the industry coined term, deadband. Deadband is the difference between the set pressure and the outlet pressure that triggers the KR to open or vent and reset. DB is a function of the friction force between the seal rings and the flow plates. As the outlet pressure slowly changes, the device will not react to the pressure change until the friction has been overcome. To reduce the deadband for greater sensitivity, an “L”, “D”, “H”, or “W” model is needed. The hydraulic pilot (“P” model) is the most sensitive KR that we offer and can achieve a deadband range of 0-100 psi. These models have a larger piston diameter which provides a larger resultant force to overcome the internal friction forces in smaller incremental adjustments. Call us today to discuss options for a new KR pressure regulator or a conversion kit.
Q: How do I prevent the KR Pressure Regulator from chattering/hammering?
A: Chattering and hammering of the KR is more than likely caused by inadequate flow capacity downstream the pressure regulator. Consider increasing the outlet pipe size, reducing restrictions and bends in the outlet piping, and/or installing an accumulator in parallel with the outlet piping.
Bladder Accumulators
Q: To what pressure should I precharge my bladder accumulator?
A: The precharge depends on the required volume and pressure of the system as well as the application. Too low or too high of a precharge can damage the bladder. For all applications, the precharge pressure should be at least 30% of the maximum system pressure. For shock absorption, the precharge is usually set to about 65% of the system pressure. For auxiliary power supply, pump supplementation, or leakage compensation it is recommended that the precharge be set between 80-90% of the minimum system pressure. For reducing line stock, the precharge should be set to about 50% of the minimum system pressure. Nevertheless, it is solely the responsibility of the user to determine the correct precharge pressure and only a qualified service technician should perform the precharge. Contact us for further recommendations.
