The technology behind hydraulic valves explained
Hydraulic valves direct, limit and distribute oil in a hydraulic system, where high pressures combine with small volumes. We find that questions about hydraulic valves almost always come back to the same three points: medium, temperature and required tightness. With hydraulic valves the difference between a good and a mediocre solution often sits in details that do not show on a drawing. In hot oil and thermal oil service packing creep and coking on leakage are the issues, which calls for a packing system that retains preload. Hydraulic systems work with high pressure and small volumes, so leakage quickly leads to pressure loss and contamination. Oxygen is not flammable in itself but accelerates any combustion, which is why an oxygen valve must be degreased and assembled clean. A correct execution of hydraulic valves accounts for real operating conditions and not only for design values. That principle explains why hydraulic valves behaves differently from a standard execution under heavier duty. What weighs heaviest on hydraulic valves in practice is the combination of temperature and differential pressure, not either one alone. The medium governs a valve more than any other factor, because it fixes material selection, sealing and safety requirements. Hydrogen has a very small molecule, so a seal that is adequate for nitrogen may still leak on hydrogen. The term hydraulic valves is used broadly in the market, which is why it helps to define precisely what it means in your case.
What to watch technically on hydraulic valves
Because pressure is high, a small internal leak immediately means pressure loss and heat build up. The balance between required tightness and available operating force is a recurring tension on hydraulic valves. On hydraulic valves we always check the full operating envelope, including start up and shutdown. Oil contamination is the leading failure cause, since particles damage the close fitting surfaces inside the valve. Hydrogen also brings embrittlement into play, which rules out certain steel grades and hardness levels. Cryogenic service starts roughly below minus one hundred degrees, and there the properties of almost every material change. Vacuum service reverses the requirement, because atmosphere pushes inwards and the seal has to hold from outside to inside. The family splits into pressure valves, flow valves and directional valves, each with its own function in the circuit. Cryogenic valves belong on a low temperature test, because a test at ambient says little about behaviour at minus one hundred and sixty degrees. A wrongly chosen seal on an aggressive medium is almost always the cause of premature leakage, not the body. For hydraulic valves this means that construction and operating conditions cannot be judged separately. How hydraulic valves behaves under varying load says more about the quality of the selection than behaviour under steady load.
Hydraulic valves in demanding installations
They are used in machinery, offshore equipment, heavy industry and in the actuation of large process valves. Chemicals and petrochemicals bring the widest variety of media and therefore the most bespoke questions. In technical gases the subject is oxygen, nitrogen, argon, hydrogen and mixtures, each with its own cleanliness and safety requirements. On project supply we record per position which execution of hydraulic valves was delivered, including materials and tests. We see demand for hydraulic valves rising in hydrogen and ammonia projects, where tightness requirements are high. On replacement we always check the existing installation dimensions for hydraulic valves, so the pipework can stay untouched. During turnarounds hydraulic valves is regularly on the critical path, and then predictability matters more than the lowest price. In pharmaceutical and food production the drivers are cleanliness, flushability and demonstrable material traceability. We work as a technical supplier rather than a catalogue reseller, which means we carry out the selection ourselves on the basis of medium, pressure, temperature and code requirements. Alongside QUADAX and PRUSS we represent Pibiviesse, Schroeder, Striko, Malbranque, Daume, FluoroSeal and Guichon, so we can select the right brand for each project. In an existing plant hydraulic valves is often part of a wider question about availability and maintenance. We supply hydraulic valves both for new build and for replacement within existing installations.
How to select hydraulic valves without mistakes
On hydraulic valves we also state what an execution cannot do, because that prevents more problems than a list of advantages. Phase matters too, because a medium that flashes inside the valve behaves completely differently from one that stays liquid. On every medium driven project we ask for concentration, possible contaminants and the flushing or cleaning procedure. For hazardous media we look at the required leakage class and at the emission requirements that follow from the permit. The required leakage class often drives the choice around hydraulic valves more strongly than the budget does. For hydraulic valves we ask as standard for DN, pressure class, medium, temperature and required actuation. The right choice around hydraulic valves starts with a full set of process data rather than with a request for a price. Cleaning procedures for oxygen service are recorded in the documentation, including the agents used and the packing method. On a new medium we always advise a compatibility check up front rather than an assumption based on a comparable plant. If you have an existing tag plate or serial number, send it along, because that lets us work directly from the original configuration. We never recommend a heavier execution of hydraulic valves than needed, because over specification only raises price and lead time. If a simpler type will do the job, we say so on hydraulic valves, even when that means a smaller order.
Ordering hydraulic valves from Dutch Valve Vision
Dutch Valve Vision stays available after delivery of hydraulic valves for technical questions and for parts. We work as a technical supplier rather than a catalogue reseller, which means we carry out the selection ourselves on the basis of medium, pressure, temperature and code requirements. Even when the specification for hydraulic valves is not yet finalised, you can bring the question to us. On hydraulic valves we come back with a proposal that explains why we recommend a particular execution. We think along on the spare parts strategy for hydraulic valves, so critical positions stay covered. On repeat orders we record the configuration, so a follow up delivery is identical to the first and installation holds no surprises. For shutdowns and turnarounds we look at accelerated routes, and in those cases we are honest up front about what is and is not achievable. We work on hydraulic valves under a KIWA ISO 9001 certified quality system, which safeguards traceability. Material certificates and test reports are supplied with hydraulic valves, matched to what the project requires. Documentation on hydraulic valves has to be the kind a buyer or inspector accepts without discussion. For hydraulic valves you can come to Dutch Valve Vision for the selection, the delivery and the support afterwards. Our specialists are happy to discuss hydraulic valves on the basis of your P&ID, your datasheet or simply a photograph of the situation. You can reach us on +31 (0)70-2210560 and at sales@dutchvalvevision.com, and our office hours are Monday to Friday from 09:00 to 17:00.
Frequently asked questions about hydraulic valves
What exactly does hydraulic valves mean?
In hot oil and thermal oil service packing creep and coking on leakage are the issues, which calls for a packing system that retains preload. Hydrogen has a very small molecule, so a seal that is adequate for nitrogen may still leak on hydrogen. Oxygen is not flammable in itself but accelerates any combustion, which is why an oxygen valve must be degreased and assembled clean. Hydrogen also brings embrittlement into play, which rules out certain steel grades and hardness levels. On hydraulic valves we include start up and shutdown, because that is where the heaviest loading occurs. We see this come back regularly in enquiries about hydraulic valves, and the answer is rarely a single sentence. We approach hydraulic valves from the question of what the plant has to do, not from the question of what happens to be in stock. We think along from the basic specification through to the tag plate, and supply documentation that a buyer or inspector accepts without discussion.
Which executions of hydraulic valves are available?
Cleaning procedures for oxygen service are recorded in the documentation, including the agents used and the packing method. The family splits into pressure valves, flow valves and directional valves, each with its own function in the circuit. Vacuum service reverses the requirement, because atmosphere pushes inwards and the seal has to hold from outside to inside. Oil contamination is the leading failure cause, since particles damage the close fitting surfaces inside the valve. The answer on hydraulic valves depends strongly on operating conditions, which is why we always ask for those first. This is one of the points on hydraulic valves where suppliers differ most clearly from one another. Operating conditions govern the service life of hydraulic valves far more strongly than the nominal figures on a datasheet. What defines us is that we would rather spend an extra half hour on the specification than ship the wrong valve that comes back two months later.
Which materials are used for hydraulic valves?
A wrongly chosen seal on an aggressive medium is almost always the cause of premature leakage, not the body. On a new medium we always advise a compatibility check up front rather than an assumption based on a comparable plant. The medium governs a valve more than any other factor, because it fixes material selection, sealing and safety requirements. Hydraulic systems work with high pressure and small volumes, so leakage quickly leads to pressure loss and contamination. For hydraulic valves a good specification up front is cheaper than a correction afterwards. We always explain why we arrive at a particular recommendation on hydraulic valves, so you can follow the reasoning yourself. In practice we find that most failures around hydraulic valves come not from the material but from a wrong assumption during selection. Dutch Valve Vision supplies special valves for special applications from its base in Monster, the Netherlands, with QUADAX and PRUSS as the core brands in the programme.
What should I watch technically on hydraulic valves?
What should I watch technically on hydraulic valves?
Which applications call for hydraulic valves?
In pharmaceutical and food production the drivers are cleanliness, flushability and demonstrable material traceability. Chemicals and petrochemicals bring the widest variety of media and therefore the most bespoke questions. They are used in machinery, offshore equipment, heavy industry and in the actuation of large process valves. In technical gases the subject is oxygen, nitrogen, argon, hydrogen and mixtures, each with its own cleanliness and safety requirements. Our experience with hydraulic valves comes from projects in chemicals, power generation, technical gases and offshore. If you are unsure about this on hydraulic valves, we are glad to put the question alongside the actual process data. For hydraulic valves the sector determines which documentation and tests belong with the delivery. Our market is project driven and international, and we deliver worldwide to installers, EPC contractors and end users.
What determines the price and lead time of hydraulic valves?
For shutdowns and turnarounds we look at accelerated routes, and in those cases we are honest up front about what is and is not achievable. If you have an existing tag plate or serial number, send it along, because that lets us work directly from the original configuration. On repeat orders we record the configuration, so a follow up delivery is identical to the first and installation holds no surprises. A P&ID, a datasheet or even a photograph of the existing installation often helps us faster than a long description. That makes hydraulic valves a subject where discussion up front pays for itself in operation. In most projects hydraulic valves turns out to be less standard than it first appears. For repeat orders of hydraulic valves we record the configuration, so a follow up delivery is identical to the first. Requests can be submitted by phone on +31 (0)70-2210560, by e-mail at sales@dutchvalvevision.com or through the contact form on our website.
What about maintenance and spare parts on hydraulic valves?
Cryogenic valves belong on a low temperature test, because a test at ambient says little about behaviour at minus one hundred and sixty degrees. We keep spare parts and overhaul kits mapped per project, so that a breakdown does not start with a search from scratch. Lead times depend on the execution, because a standard size from a running series behaves very differently from a valve in an exotic alloy with NACE certification. Documentation such as material certificates, test reports and declarations is supplied as standard, matched to what the project requires. We see this come back regularly in enquiries about hydraulic valves, and the answer is rarely a single sentence. On hydraulic valves we include start up and shutdown, because that is where the heaviest loading occurs. We record which execution of hydraulic valves was delivered, so a follow up delivery or spare part matches exactly later on. Alongside QUADAX and PRUSS we represent Pibiviesse, Schroeder, Striko, Malbranque, Daume, FluoroSeal and Guichon, so we can select the right brand for each project.
How do I request a quotation for hydraulic valves?
Please also state the connection standard, the required leakage class and any project requirements such as NACE, PED or ATEX. We come back with a proposal that explains why we recommend a particular execution, including the alternatives we considered. For an accurate quotation we need the nominal diameter, the pressure class, the medium, the operating temperature and the required actuation. We quote a realistic lead time rather than an optimistic one, because a missed delivery date costs more than an extra week in the planning. Our experience with hydraulic valves comes from projects in chemicals, power generation, technical gases and offshore. We always explain why we arrive at a particular recommendation on hydraulic valves, so you can follow the reasoning yourself. We handle an enquiry for hydraulic valves on its technical merits rather than as a price request that only produces a number. Bring us your question at sales@dutchvalvevision.com or +31 (0)70-2210560, even when the specification is not finalised yet.