Selection Strategy of hydraulic oil additive packages under Different Working Conditions

In industrial production, hydraulic systems are the core of power transmission and control, while hydraulic oil additives, as the "performance core carrier" of hydraulic oil, directly determine the operating precision, component lifespan, and operation and maintenance costs of hydraulic systems. Whether it is the high-pressure and heavy-load conditions of construction machinery, the precise control requirements of machine tool equipment, the extreme tests of high-temperature environments, or the corrosion challenges of marine engineering, selecting the right hydraulic oil additives is the key to avoiding failure risks and reducing overall costs. Based on over 10 years of practical experience in the lubricant additives industry, this article will combine the measured data and product system of UNPChemicals to systematically analyze the selection logic for different operating conditions and provide practical solutions that can be directly implemented for potential customers.

hydraulic oil additive package is a compound chemical product formulated by scientifically proportioning various functional additives such as anti-wear agents, anti-corrosion agents, antioxidants, anti-foaming agents, demulsifiers, and viscosity index improvers. Its core function is to endow base oils (mineral oil, synthetic oil, coal-based oil, etc.) with targeted core performance, addressing common issues such as wear, corrosion, oxidative deterioration, foam generation, and oil-water emulsification faced during the operation of hydraulic systems. Simply put, base oil is the "carrier" of hydraulic oil, while the compound additive is the key to determining the "capability boundary" of hydraulic oil.

UNPChemicals is a professional supplier of high-quality and high-performance hydraulic oil additives, having been deeply involved in the industry for many years. Relying on strict R&D standards and actual measurement verification, it has built a comprehensive product system covering different application scenarios. Its core products include high-zinc hydraulic oil additive UNP AH502A, low-zinc hydraulic oil additive UNP AH502B, ashless hydraulic oil additive UNP AH502C, etc. All products have passed multiple domestic and international authoritative standard certifications such as GB11118.1-2011, DIN 51 524, AFNOR NF E 48-603, Eaton Vickers I-286-S, etc., and are compatible with various base oils such as mineral oil, synthetic oil, CTL (coal-to-liquid), etc., meeting the full-scenario requirements from ordinary industries to high-end precision equipment.

From an industry practice perspective, the core value of hydraulic oil additive packages lies in "operating condition adaptability": different scenarios have significantly different performance priorities for hydraulic oil - heavy - load scenarios require enhanced anti - wear and load - bearing capabilities, precision scenarios need to focus on cleanliness and stability, high - temperature scenarios need to emphasize oxidation resistance and thermal stability, and corrosive environments require enhanced anti - corrosion and anti - rust properties. UNPChemicals' three core products were developed precisely based on this logic. By adjusting the zinc content and additive ratio, a product matrix of "high - zinc heavy - load type, low - zinc balanced type, and ashless clean type" has been formed, providing customers with precisely matched solutions.

The hydraulic systems of construction machinery (such as excavators, loaders, cranes, road rollers, etc.) are typical representatives of "high pressure, heavy load, and harsh working conditions". Their core working condition characteristics include: working pressure generally ranging from 30 to 40 MPa (up to 50 MPa under extreme conditions), large load fluctuations with high-frequency impacts, a dusty working environment, easy mixing of moisture (rainwater, groundwater), a wide temperature range (-20°C to 60°C), and long continuous operation time (8 to 12 hours per day on average). In response to these characteristics, compound additives need to meet the four core requirements of "strong anti-wear, anti-pollution, anti-oxidation, and wide temperature adaptability".

(1) Core performance requirements and product adaptation

1. Superb anti-wear performance and high load-carrying capacity

Key components such as hydraulic pumps, motors, and valve spools in construction machinery are prone to be in boundary lubrication or even extreme pressure lubrication conditions under high pressure, with a high risk of direct friction on metal surfaces. Without sufficient anti-wear protection, failures such as wear, seizure, and spalling may occur, leading to equipment downtime. Therefore, the compound additive must be able to form a strong chemical lubricating film on the metal surface to resist high-pressure friction and extreme pressure impact.

UNP AH502A, as a high-zinc hydraulic oil additive package, is the preferred product for construction machinery applications. With a zinc content as high as 7.2wt%, combined with 13.5wt% sulfur content and 6.5wt% phosphorus content, it forms a powerful anti-wear - extreme pressure system. Measured data shows (base oil is 46# Group II base oil, additive dosage 0.6%): the hydraulic oil formulated with this product has a wear scar diameter of only 0.46mm under the conditions of 392N load, 75°C, and 1200r/min, a PB value (maximum non-seizure load) of 90kg, a PD value (extreme pressure load) as high as 126kg, and a gear machine test failure level of no less than 10, effectively extending the service life of hydraulic pumps and motors by more than 30%.

2. Excellent anti-emulsification and contamination tolerance

Moisture and dust are the "invisible killers" of the hydraulic systems of construction machinery: moisture can cause oil emulsification, lubricating film rupture, and metal corrosion; dust can accelerate component wear and clog filters. Therefore, the compound agent needs to have rapid demulsification ability and high pollution tolerance.

UNP AH502A and UNP AH502B excel in demulsibility: the demulsification time of UNP AH502A (at 54°C, 40-37-3 standard) is only 7 minutes, while that of UNP AH502B is even shorter at 5 minutes, both far lower than the industry standard of ≤30 minutes, enabling rapid oil-water separation; even when the oil contains 2% water, the filtration efficiency of UNP AH502B (83.8% in Stage I, 65.4% in Stage II) still meets industrial requirements, reducing the frequency of filter clogging.

3. Excellent oxidation resistance and wide temperature adaptability

Long-term high-temperature operation will accelerate the oxidation and deterioration of hydraulic oil, generating sludge and carbon deposits, leading to an increase in oil viscosity and performance degradation; while the wide temperature difference in outdoor operations requires the compound additive to balance low-temperature fluidity and high-temperature stability.

UNP AH502A's antioxidant performance is particularly outstanding, with the rotary oxygen bomb test (150°C) result reaching 432 minutes, far exceeding the industry average (300 minutes), and it can extend the oil change interval to over 5000 hours; its flash point (COC) is 140°C, it is not easily volatile at high temperatures, and it can still maintain good fluidity at a low temperature of -20°C, meeting the requirements of wide-temperature operation.

(2) Comparison Table of Performance of Compound Agents in Construction Machinery Scenarios

(3) Selection Recommendations

High-pressure and heavy-load scenarios (such as excavators, cranes): UNP AH502A is the preferred choice, as its super wear resistance and high load-bearing capacity can perfectly adapt to extreme working conditions;

Scenarios with high environmental protection requirements or medium load (such as loaders, road rollers): Choose UNP AH502B, whose low-zinc formula balances anti-wear, anti-emulsification, and environmental adaptability, meeting the needs of most construction machinery.

The core requirement of the precision hydraulic system of machine tools (CNC lathes, machining centers, grinders, etc.) is "high-precision control", with operating conditions characterized by medium working pressure (10-20 MPa), smooth operation, extremely high positioning accuracy requirements (error ≤ 0.001 mm), strict requirements for hydraulic oil cleanliness (below NAS 6), and long continuous operation time (8-24 hours). Therefore, the selection of compound additives needs to focus on the three core points of "high cleanliness, low wear, and strong stability".

(1) Key Points of Core Selection and Product Adaptation

1. Extreme filtration performance and low impurity generation

The gaps between precision components of machine tools (spool valves, servo valves) are extremely small (≤0.01mm). Impurities or sludge can cause spool valve jamming, action lag, affect machining accuracy, and even damage servo valves (repair costs amount to tens of thousands of yuan). Therefore, the compound agent must have excellent filtration performance and be less likely to form deposits during long-term operation.

UNP AH502B is an ideal choice for machine tool scenarios: in a moisture-free environment, the filtration efficiency is 95.0% in Stage I and 93.2% in Stage II; when containing 2% moisture, it is 83.8% in Stage I and 65.4% in Stage II, far exceeding industry standards (moisture-free ≥80%, with moisture ≥70%). Its thermal stability test (135°C, 168h) shows that the total sediment weight is only 4.21mg/100ml, the weight loss of the copper rod is 0.8mg/200ml, with almost no sludge formation, and it can maintain the cleanliness of hydraulic oil for a long time.

2. Stable anti-wear performance and protection of non-ferrous metals

Although the pressure of the machine tool hydraulic system is relatively low, continuous operation results in a significant cumulative wear effect, and there are non-ferrous metal components such as copper and aluminum in the system, requiring a compound agent to balance anti-wear and anti-corrosion properties.

The wear scar diameter (392N, 60min) of the hydraulic oil formulated with UNP AH502B is 0.48mm, and the failure level in the gear machine test is not lower than level 10, effectively protecting hydraulic pumps and servo valves. The copper strip corrosion test (100℃, 3h) result is grade 1a, indicating no corrosion to non-ferrous metals, and it meets authoritative certifications in the machine tool industry such as Denison HF-0 (T6H20C mixed pump) and Eaton Vickers M-2950-S (35VQ25), with good compatibility with mainstream machine tool brands.

3. Excellent anti-foaming and air release properties

Foam can cause system pressure fluctuations and a decrease in action precision; air entrapment can lead to cavitation wear, affecting component lifespan. UNP AH502B has a foam volume/defoaming time of 20/0 ml/ml across the full temperature range (24°C, 93.5°C, and after recovery at 24°C), far lower than the industry standard of ≤150/0 ml/ml, eliminating the need for additional antifoaming agents; its air release time (at 50°C) is only 3 minutes, far lower than the 10-minute standard, enabling rapid air expulsion and preventing cavitation.

(2) Key Points Table for Selection of Machine Tool Precision System Compound Agents

(3) Selection Recommendations

Medium and high-end machine tool precision hydraulic systems (such as machining centers, grinders): UNP AH502B is the preferred choice, as its high filtration, low wear, and excellent anti-foaming properties are perfectly suited to the requirements of high precision and long-term operation;

High-end environmentally friendly machine tool scenario: Choose UNP AH502C ashless compound, whose ashless formula has no risk of metal salt precipitation, and also features excellent filterability and oxidation resistance, meeting the requirements of clean hydraulic systems.

The operating temperature of hydraulic systems in high-temperature environments (such as metallurgy, casting, glass processing, and hydraulic systems supporting chemical reaction kettles) is typically between 60°C and 100°C, and can reach over 120°C under extreme operating conditions. High temperatures accelerate the oxidation and deterioration of hydraulic oil, the failure of additives, and the formation of sludge, while also intensifying component corrosion. Therefore, the core of selection for high-temperature scenarios is "stability control," with a focus on three key performance indicators: oxidation resistance, thermal stability, and hydrolytic stability.

(1) Core stability requirements are adapted to the product

1. Extreme antioxidant performance

Under high temperature, the oxidation reaction rate of hydraulic oil increases exponentially, and the generated acidic substances and sludge will corrode metal components and clog filters. The compound additive needs to have strong antioxidant capacity to delay the oxidation of the oil.

All three products of UNPChemicals have performed excellently: UNP AH502A achieved 432 minutes in the Rotary Oxygen Bomb Test (150°C), and its oil change interval can be extended to over 8,000 hours; UNP AH502C ashless compound uses a special ashless antioxidant formula, which can effectively inhibit high-temperature free radical reactions and is suitable for high-temperature scenarios with extremely high requirements for deposit control; UNP AH502B achieved 387 minutes in the Rotary Oxygen Bomb Test, meeting the requirements of medium-high temperature operating conditions from 60°C to 80°C.

2. Excellent thermal stability and low deposit formation

Under high temperature, the compound itself must be stable, not easily decompose or become ineffective, and should not generate excessive deposits. The thermal stability test of UNP AH502A (135°C, 168h) shows that the weight loss of the copper rod is 0.1mg/200ml, the weight loss of the steel rod is 0.85mg/200ml, the acid value change rate is 0.90%, the viscosity change rate at 40°C is 1.42%, the total deposit is only 3.0mg/100ml, the appearance of the copper and steel rods shows no discoloration, and there is almost no decomposition under high temperature; UNP AH502B has a total deposit of 4.21mg/100ml and stable performance; UNP AH502C has an ashless formula with with with no risk of metal salt decomposition and extremely low deposit generation.

3. Good hydrolytic stability

In high-temperature environments, moisture in the air is prone to condense and mix into hydraulic oil, triggering hydrolysis reactions to generate acidic substances that corrode metal components. UNP AH502A and UNP AH502B exhibit excellent hydrolytic stability: UNP AH502A has a copper strip weight loss of 0.02mg and a total acidity of the water layer of 0.03mgKOH/g; UNP AH502B has a copper strip weight loss of 0.02mg and a total acidity of the water layer of 0.01mgKOH/g, both far below the industry limits, and can withstand the hydrolysis risk of high-temperature moisture.

(2) Comparison Table of Performance of High-Temperature Environment Compound Agents

(3) Selection Recommendations

Extreme high temperature conditions (80°C - 120°C, such as metallurgy and glass processing): UNP AH502A is the preferred choice, as its excellent oxidation resistance and thermal stability can delay oil deterioration to the greatest extent;

Medium to high temperature conditions (60°C - 80°C, such as those associated with chemical reaction kettles): Select UNP AH502B to balance oxidation resistance, cleanliness, and cost;

High-temperature clean-type scenarios (such as precision high-temperature equipment): Choose UNP AH502C, featuring low deposits and high hydrolytic stability, to ensure long-term clean operation of the system.

5. Anti-corrosion and anti-rust design of hydraulic oil additive packages in ocean engineering

The hydraulic systems of ocean engineering (offshore platforms, ship hydraulic systems, coastal cranes, etc.) face a unique corrosive environment of "high salt spray, high humidity (≥85%), easy seawater intrusion, and large temperature difference (-10°C to 50°C)", where metal components are prone to electrochemical corrosion and seawater corrosion. Therefore, the core of compound selection is "comprehensive anti-corrosion and anti-rust", which needs to cover the protection of ferrous and non-ferrous metals, while also having anti-emulsification properties and wide temperature adaptability.

(1) Core anti-corrosion and anti-rust requirements are compatible with the product

1. Strong multi-metal anti-corrosion and anti-rust performance

In the marine environment, steel components are prone to rust, while non-ferrous metals such as copper and aluminum are prone to pitting corrosion. All three UNPChemicals products have passed rigorous tests: in the liquid-phase rust prevention test (24h), they achieved "rust-free" in both distilled water and artificial seawater environments, meeting the GB/T 11143 (ASTM D665) standard; in the copper strip corrosion test (100°C, 3h), they were all rated 1a (GB/T 5096), showing no corrosion to copper and copper alloys. Among them, UNP AH502C is added with a special multi-metal corrosion inhibitor, which can form a dense protective film to resist salt spray and seawater erosion, making it suitable for high-end marine engineering scenarios.

2. Rapid demulsification and seawater pollution tolerance

Seawater can easily mix with hydraulic oil, and emulsification can lead to the rupture of the lubricating film and the failure of anti-corrosion. The demulsification time of UNP AH502B is only 5 minutes, and that of UNP AH502A is 7 minutes, both of which are far lower than the ≤30-minute standard, enabling rapid separation of seawater. Even when containing 2% seawater, the filtration performance of both products remains stable without clogging the filter. All three products have good water separation properties, reducing the residence time of water and lowering the risk of hydrolysis corrosion.

3. Wide Temperature Adaptability and Long-Term Stability

The marine environment has a large temperature difference and requires long-term operation in a high-humidity and high-salt environment. UNP AH502A, AH502B, and AH502C all balance low-temperature fluidity and high-temperature stability: UNP AH502A has a rotary oxygen bomb time of 432 minutes, and its oil change interval can reach over 6000 hours; UNP AH502C's ashless formula has no risk of metal salt precipitation, making it suitable for long-term operation in high-humidity environments.

(2) Anti-corrosion and anti-rust performance table of marine engineering compound agents

(3) Selection Recommendations

Scenarios prone to seawater mixing (such as offshore platforms and ships): UNP AH502B is the preferred choice, with its rapid demulsification and strong anti-corrosion properties to resist seawater erosion;

Overloaded marine equipment (such as coastal cranes, port machinery): Select UNP AH502A to balance anti-wear and anti-corrosion properties;

High-end offshore engineering (such as deep-sea operation machinery): Select UNP AH502C, whose multi-metal anti-corrosion and low sediment characteristics ensure the long-term stable operation of equipment.

The core of selecting hydraulic oil additive packages is "working condition adaptation" - construction machinery focuses on "anti-wear + anti-pollution", machine tool precision systems focus on "filterability + stability", high-temperature environments focus on "oxidation resistance + thermal stability", and offshore engineering focuses on "anti-corrosion + anti-emulsification". As a professional supplier, UNPChemicals' three products, UNP AH502A, UNP AH502B, and UNP AH502C, cover the full range of high-zinc, low-zinc, and ashless products. Through rigorous actual testing and authoritative certification, they can precisely meet the requirements of different working conditions.

The price of Hydraulic Oil Additives Package varies depending on factors such as brand, specification, composition, and sales channels. If you are interested in Hydraulic Oil Additives Package, please feel free to contact us.

UNPChemicals is a professional supplier of high-quality and effective Hydraulic Oil Additives Package. We offer several remarkable products, namely High zinc hydraulic oil additives UNP AH502A,Low Zinc Hydraulic Oil Additives UNP AH502B,Zinc-free Hydraulic Oil Additives UNP AH502C,etc.

High zinc hydraulic oil additives UNP AH502A are a type of chemical additive used in hydraulic oils that contain high levels of zinc dialkyldithiophosphate (ZDDP). ZDDP is a well-known anti-wear agent that also provides antioxidant, anti-corrosion, and anti-foam properties. The zinc in these additives plays a crucial role in forming a protective film on metal surfaces within the hydraulic system, thereby reducing wear and extending the life of the system components.

Low Zinc Hydraulic Oil Additives UNP AH502B are a class of advanced lubricant additives designed to enhance the performance of hydraulic oils with reduced zinc content.These additives are formulated to provide a balance of anti-wear,extreme pressure,and antioxidant properties,making them suitable for modern hydraulic systems that demand high performance with lower environmental impact.

Zinc-free Hydraulic Oil Additives UNP AH502C are a new class of environmentally friendly lubricant additives designed for hydraulic systems.These additives are formulated to provide the same level of performance as traditional zinc-containing additives but without the heavy metal content,reducing the environmental impact of hydraulic fluids.

UNPChemicals,aka Luoyang Pacific United Petrochemical Co., Ltd., focuses on the application and development of special lubricating grease additives such as MODTC, MODTP, molybdenum amide, thiadiazole metal deactivators, and phosphate esters. With nearly 30 products in seven series, including extreme pressure anti-wear additives and special grease additives, it is a global manufacturer of special lubricating grease additives and a national high-tech enterprise with great influence and leading role in the industry. If you are looking for Lubricant Additive or technical information, feel free to contact UNPChemicals.