Diagnosis and Solutions for Common Problems of Hydraulic Oil Additives Package

In the stable operation of industrial hydraulic systems, the performance of hydraulic oil plays a central role, and hydraulic oil additives, as a key component for enhancing the comprehensive performance of hydraulic oil, directly affect equipment lifespan and production efficiency through their selection, application, and problem handling. Starting from a basic understanding of hydraulic oil additives, this article combines real-world industry cases with UNPChemicals' professional product system to provide scientific diagnostic approaches and highly practical solutions for common issues such as sludge formation, filter clogging, foaming, and insufficient air release performance, offering practical references for potential customers such as hydraulic oil production enterprises and equipment maintenance teams.

1. What is a hydraulic oil Additives Package?

Hydraulic oil Additives Package are a functional additive combination composed of various single agents such as anti-wear agents, anti-rust agents, antioxidants, anti-foaming agents, metal deactivators, anti-emulsifiers, etc., formulated through scientific compounding. Its core function is to endow base oils (such as mineral oils, synthetic oils, or CTL base oils) with excellent anti-wear, anti-rust, anti-oxidation, anti-foaming, and other properties, meeting the stringent requirements of hydraulic systems for oil under different working conditions - for example, extending the service life of hydraulic pumps, preventing corrosion of metal components, inhibiting high-temperature aging of oil, and ultimately ensuring the efficient and stable operation of hydraulic systems.

As a professional R&D and supply enterprise in the hydraulic oil compound industry,  UNPChemicals  has been deeply involved in the field of high-performance compounds, committed to "making additives simple", and has a complete product matrix of hydraulic oil compounds under its umbrella, which can cover application scenarios with different environmental protection standards and different load requirements:

• High-Zinc Anti-Wear Hydraulic Oil Compound UNP AH502A: With a zinc content of 7.2% (wt), it has outstanding anti-wear performance, excellent rust prevention, oxidation resistance, and high load-carrying capacity. It can be used to formulate high-performance anti-wear hydraulic oils that meet multiple international standards such as GB11118.1-2011 and DIN51524, and is especially suitable for industrial hydraulic systems with high anti-wear requirements;

• Low-Zinc Hydraulic Oil Compound UNP AH502B: While retaining the basic anti-wear performance, it reduces the zinc content, taking into account both environmental protection and equipment compatibility, and is suitable for scenarios with certain restrictions on heavy metal content;

• Zinc-Free Hydraulic Oil Compound UNP AH502C: Completely free of zinc components, compliant with stringent environmental regulations (such as the European Union RoHS), suitable for hydraulic systems with extremely high environmental requirements, such as those in electronics and food machinery.

All these products have undergone strict performance verification. Taking UNP AH502A as an example, after adding 0.6% of it to 46#Ⅱ base oil, the PB value (maximum non-seizure load) reaches 90kg, the PD value (sintering load) reaches 126kg, and the result of the rotary oxygen nitrogen test (150℃) is 432min, far exceeding the industry's basic standards, fully demonstrating the reliability and professionalism of UNPChemicals products.

2. Analysis of Complex Agent Factors in Sludge Formation in Hydraulic Systems

The formation of sludge in hydraulic systems is one of the main causes of equipment failure and shortened oil service life. Its essence is that hydraulic oil degrades under the influence of high temperature, oxidation, and contaminants, forming viscous deposits. From the perspective of Additives Package, the core inducements for sludge formation can be summarized into the following three points, which can be specifically avoided by leveraging the performance advantages of UNP AH502A:

Insufficient antioxidant efficacy leads to accelerated oxidative degradation of the oil

When hydraulic oil operates at high temperatures for a long time (such as when the system oil temperature exceeds 60°C), the base oil molecules are prone to oxidation, generating polar substances such as carboxylic acids, aldehydes, and ketones. These substances further polymerize to form sludge. If the antioxidant content in the Additives Package is insufficient or the type is mismatched, it will be unable to effectively capture oxidation free radicals, leading to the runaway of the oxidation chain reaction.

Case Reference: A mechanical manufacturing plant used hydraulic oil formulated with a common Additives Package. After 3 months of continuous operation, the system oil temperature rose to 55°C, the acid value of the oil increased from 0.3mgKOH/g to 1.8mgKOH/g, and obvious brown sludge appeared at the bottom of the oil tank. Subsequently, the plant switched to using UNP AH502A Additives Package (with an addition amount of 0.7%), which contains high-efficiency antioxidant components that can significantly delay oxidation. According to performance data, the rotating oxygen nitrogen test (150°C) of the oil formulated with UNP AH502A reached 432 minutes, more than 1.5 times that of the common Additives Package, effectively inhibiting oxidative degradation at high temperatures. After long-term use, the acid value change rate was only 0.9% (data from the 135°C, 168h thermal stability test), significantly reducing the risk of sludge formation.

The rust inhibitor reacts with metal ions to produce chelated deposits

Metal components such as copper and iron in hydraulic systems, if they have poor compatibility with the rust inhibitor in the Additives Package, may undergo chemical reactions to form metal soap deposits. After mixing with oxidation products, these deposits will accelerate the formation of sludge. For example, the rust inhibitor (such as ordinary carboxylic acid soap) used in some low-quality Additives Package easily combines with copper ions in an acidic environment to form blue flocculent precipitates, which ultimately transform into sludge.

UNP AH502A Solution: It uses a dedicated anti-rust - metal passivation composite system. In the copper strip corrosion test (100°C, 3h), it is only grade 1a (GB/T 5096 standard), the weight loss of the copper rod is only 0.1mg/200ml (135°C, 168h thermal stability test), and the weight loss of the steel rod is 0.85mg/200ml. It can effectively inhibit the dissolution of metal ions and avoid the adverse reactions between anti-rust agents and metal ions. Meanwhile, in the liquid-phase rust test (24h), there is no rust in both distilled water and artificial seawater, further verifying the stability of the anti-rust system and reducing the sludge problem caused by chelated deposits.

Poor anti-emulsification performance, water causes sludge agglomeration

If the hydraulic system admits moisture due to seal failure or a humid environment, and the anti-emulsification performance of the compound is insufficient, the moisture will form a stable emulsion with the oil. The emulsion is prone to causing hydrolysis of the base oil and failure of additives at high temperatures, and the resulting polar substances will adsorb contaminants such as dust and metal debris, ultimately agglomerating into sludge.

Key Data Support: The demulsibility test result of UNP AH502A blending oil (40-37-3, 54°C) is only 7 minutes (GB/T 7305 standard, with the index requirement ≤30 minutes), far superior to the industry average. It can quickly achieve oil-water separation and prevent water from remaining in the system. Even under operating conditions with 2% water content, its filtration performance remains stable (filtration performance is 122 without water and 144 with 2% water), effectively preventing sludge agglomeration caused by water.

3. Compound Agent Solution to Filter Clogging Problem

Filter clogging is a common fault in hydraulic systems, manifested by abnormal increases in system pressure, decreases in flow rate, and in severe cases, can lead to pump body cavitation and valve jamming. From the perspective of compound agents, the main causes of clogging are poor solubility of the compound agent in base oil, precipitation, or reaction with system contaminants to form non-filterable impurities. Considering the product characteristics of UNP AH502A, solutions can be developed from the following three dimensions:

Select highly soluble compounding agents to avoid precipitation of additives

Some compound agents tend to precipitate solid particles in low-temperature environments (such as winter storage temperatures below 5°C) due to the use of high-melting-point single agents (such as certain anti-wear agents) in their formulations or poor compatibility with base oils. After these particles enter the filter with the oil, they can block the pore size of the filter element (common filter element pore sizes are 3-10μm).

Advantages of UNP AH502A: It has excellent solubility in a wide range of base oils, including Group I and Group II mineral oils, as well as synthetic oils and CTL base oils. The product itself is a yellow transparent liquid (at 20°C), with no visible impurities to the naked eye, a kinematic viscosity (at 40°C) of 175 mm²/s, and can form a homogeneous system after mixing with base oils, without delamination or precipitation. Even after 72 hours of low-temperature storage at 0°C, it still maintains a transparent state, does not precipitate solids due to temperature changes, and reduces the risk of filter clogging from the source.

Optimize the detergency and dispersibility of the compound agent to prevent the agglomeration of impurities

In hydraulic systems, solid impurities such as metal debris (e.g., iron filings generated by pump wear) and dust are inevitably produced. If the detergent-dispersant performance of the compound is insufficient, these impurities will agglomerate in the oil to form large particles (diameter exceeding the pore size of the filter element), leading to rapid clogging of the filter.

Test Verification: The thermal stability test (135°C, 168h) of UNP AH502A blended oil showed that the total sediment weight was only 3.0mg/100ml (the index requirement is ≤100mg/100ml), far lower than the industry average. This indicates that the detergent-dispersant components it contains can encapsulate and disperse minute impurities within the system, preventing them from agglomerating into large particles, ensuring that impurities can be effectively intercepted by the filter rather than clogging the filter element. Meanwhile, its filtration performance remains stable under water-containing conditions (filtration performance is 144 with 2% water, close to 122 without water), further demonstrating that even in the presence of moisture, no clogging impurities will be generated due to the reaction between additives and water.

Control the sulfur and phosphorus content of the compounding agent to avoid the formation of metal salts

The sulfur and phosphorus elements in the compound are important sources of anti-wear performance, but if the sulfur and phosphorus content is too high and reacts with metal ions (such as zinc and iron) in the system, it may form solid salts such as sulfides and phosphates. These salts have high hardness, fine particles, and are prone to clogging filters and difficult to clean.

Scientific formulation of UNP AH502A : Its sulfur content is 13.5% (wt), phosphorus content is 6.5% (wt), and zinc content is 7.2% (wt). The three form a synergistic anti-wear system (PB value 90kg, PD value 126kg), while avoiding the formation of salts caused by excessive sulfur and phosphorus. Verified by the hydrolysis stability test (SH/T 0301), its copper strip weight loss is only 0.02mg, and the total acidity of the water layer is 0.03mgKOH/g, indicating that in a water environment, the sulfur and phosphorus components are not easily hydrolyzed to form acidic substances, nor will they react with metal ions in large quantities to form solid salts, effectively reducing the probability of filter blockage.

4. Compound Adjustment Strategy for Hydraulic Oil Foaming Phenomenon

The foaming phenomenon of hydraulic oil is manifested by the appearance of a large amount of foam on the oil surface or the generation of cavitation within the system, which can lead to system pressure fluctuations, increased noise, and even cause idling damage to the pump. The generation of foam is directly related to the anti-foaming performance of the compound agent - if the type of anti-foaming agent is inappropriate, the addition amount is insufficient, or the compatibility with other additives is poor, it will all result in the difficulty of eliminating foam. Combining the anti-foaming advantages of UNP AH502A, the following adjustment strategies can be adopted:

Select a compound agent with a built-in high-efficiency anti-foaming system, eliminating the need for additional anti-foaming agents

Some compound agents lack antifoaming agents or have insufficient antifoaming agent efficacy, so additional silicone-based antifoaming agents (such as polydimethylsiloxane) need to be added when formulating hydraulic oil. However, excessive addition can lead to a decline in the air release performance of the oil, which in turn causes foam problems.

Core Advantages of UNP AH502A: Its formulation already integrates an efficient anti-foaming system, so there is no need to add additional anti-foaming agents when blending hydraulic oil to meet stringent anti-foaming requirements. According to performance data, the results of the foam characteristics test (ASTM D892) of its blended oil are as follows:

• Procedure I (24°C): 20/0 ml/ml (Indicator requirement ≤150/0);

• Procedure II (93.5°C): 10/0 ml/ml (specification requirement ≤75/0);

• Procedure III (post 24°C): 10/0 ml/ml (specification requirement ≤150/0).

Whether under normal temperature or high temperature conditions, the foam generation is low and the dissipation speed is fast, fully meeting the anti-foaming requirements of industrial hydraulic systems and avoiding performance fluctuations caused by additional anti-foaming agents.

Balance the ratio of anti-foaming agent to air release agent to avoid the "anti-foaming - air release" conflict

The function of anti-foaming agents is to inhibit foam generation, while that of air release agents is to accelerate the escape of dissolved air in oil. If the ratio between the two is imbalanced, it may lead to the contradiction of "good anti-foaming effect but slow air release" or "fast air release but excessive foam". For example, some Additives Package use high-content silicone anti-foaming agents, which, although capable of inhibiting foam, form microbubbles in the oil, resulting in an extended air release time.

Collaborative Design of UNP AH502A : The ratio of antifoam agent to air release agent in its formulation has been precisely optimized. While ensuring antifoam performance, its air release property still performs excellently. According to test data, the air release time of its blended oil at 50°C is only 3 minutes (the specification requires ≤10 minutes, 46# base oil), far faster than the industry average (usually 5 - 8 minutes). This means that even if a small amount of air is dissolved in the oil, it can quickly escape, without forming stable foam or air pockets, completely resolving the conflict between "antifoam - air release".

Adjust the compound agent for high-temperature working conditions to prevent the anti-foaming agent from failing

In high-temperature hydraulic systems (such as the hydraulic systems of metallurgical equipment, where the oil temperature often reaches 80-100°C), ordinary anti-foaming agents are prone to decomposition and failure due to high temperatures, leading to the generation of a large amount of foam. At this time, a high-temperature-resistant anti-foaming system needs to be selected to ensure that the compound agent can still maintain its anti-foaming performance at high temperatures.

High-temperature stability of UNP AH502A: Its flash point (open cup) reaches 140°C (GB/T 3536), far higher than the maximum oil temperature of common hydraulic systems (usually ≤100°C), indicating that its antifoam component is not easily decomposed at high temperatures. Verified by the foam procedure II test at 93.5°C, its foam generation is only 10/0 ml/ml, close to its performance at room temperature, proving that it can still effectively inhibit foam under high-temperature operating conditions and is suitable for hydraulic systems in high-temperature environments such as metallurgy and forging.

5. Improvement Measures for Insufficient Air Release Performance

Insufficient air release performance of hydraulic oil means that the dissolved air in the oil cannot escape quickly, forming tiny bubbles within the system. These bubbles lead to increased compressibility of the oil, delayed system response, and simultaneously accelerate oil oxidation (due to the increased contact area between oxygen in the bubbles and the oil), shortening the oil's service life. From the perspective of additives, improving air release performance requires starting from three directions: "accelerating bubble escape", "reducing air dissolution", and "enhancing high-temperature stability". Combining with the technical characteristics of UNP AH502A, the specific measures are as follows:

Add high-efficiency air release agent to shorten the bubble escape time

The core function of air release agents is to reduce the surface tension of oil, disrupt the stability of bubbles, promote the aggregation of tiny bubbles into large ones, and facilitate their rapid upward floating and escape. If the content of air release agents in the compound is insufficient or the type is mismatched, it will lead to an extended air release time.

Effectiveness Verification of UNP AH502A: A special fatty amine air release agent has been added to its formulation, which has good compatibility with the base oil and can act quickly. According to the SH/T 0308 standard test, the air release time of its blended oil at 50°C is only 3 minutes, far lower than the industry standard requirement of ≤10 minutes (46# base oil). Even when a high dosage of 0.8% is added, the air release time can still be controlled within 4 minutes, meeting the stringent requirements of high-load hydraulic systems (such as injection molding machines and excavators) for air release performance.

Optimize the formulation of the compounding agent to reduce the solubility of air in oil

Certain components in the compound agent (such as some polar anti-wear agents) increase the solubility of air in the oil, causing more air to dissolve in the oil and thus prolonging the release time. Therefore, to improve air release performance, additives with low air solubility should be selected as much as possible while ensuring core properties such as anti-wear and anti-rust.

Formula Optimization of UNP AH502A: It adopts the combination of "low-polarity anti-wear system + high-efficiency anti-rust agent", which, while ensuring anti-wear performance (PB value 90kg) and anti-rust performance (no rust in liquid-phase corrosion), minimizes air solubility. Through comparative tests, it was found that the air solubility of UNP AH502A formulated oil is 15%-20% lower than that of ordinary compound formulated oil, meaning that under the same working conditions, it dissolves less air, has a lighter air release burden, and further shortens the release time.

Improve the high-temperature stability of the compounding agent and prevent the degradation of air release performance at high temperatures

Under high-temperature operating conditions, the viscosity of the oil decreases, the solubility of air in the oil increases, and at the same time, some air release agents may become ineffective due to high-temperature decomposition, leading to a decline in air release performance. Therefore, improvement measures need to take into account the high-temperature stability of the Additives Package.

High-temperature performance of UNP AH502A: Verified by the thermal stability test at 135°C for 168 hours, the viscosity change rate of its formulated oil at 40°C is only 1.42%, and the acid value change rate is 0.90%, indicating that the oil performance remains stable at high temperatures, and the air release agent does not undergo significant decomposition. Meanwhile, it still maintains excellent anti-foaming performance (10/0 ml/ml) in the foam test at 93.5°C, indirectly proving that the air release agent can still function properly at high temperatures. Even in a hydraulic system with an oil temperature of 80°C, its air release time can still be controlled within 5 minutes, meeting the requirements for use under high-temperature conditions.

Conclusion

The selection and application of hydraulic oil Additives Package are directly related to the stable operation of hydraulic systems and the service life of equipment. In response to common problems such as sludge formation, filter clogging, foaming, and insufficient air release performance, comprehensive diagnosis and solutions are required from the perspectives of the performance characteristics, formulation design, and working condition adaptability of Additives Package.

The Price of Hydraulic Oil Additives Package

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.

Supplier of Hydraulic Oil Additives Package

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.

Professional Lubricant Additive Manufacturer

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.