Comparison of Differences and Selection of High-Zinc / Low-Zinc / Ashless Hydraulic Oil Additives

1. What is a hydraulic oil additive package?

2. Differences in Formulations and Applicable Scenarios of Three Types of Hydraulic Oil Compounding Agents

Comparison Table of Core Basic Parameters of Three Types of Hydraulic Oil Compound Agents

(1) High-Zinc Hydraulic Oil Compound Additive (UNP AH502A)

Core Features of the Formula

Core Performance Advantages

1. Extreme pressure and anti-wear performance: The wear scar diameter is only 0.46mm, the maximum non-seizure load (PB value) reaches 90kg, the sintering load (PD value) reaches 126kg, the failure level of the gear machine test is not less than 10, far exceeding the requirements of industry standards, providing extremely strong boundary lubrication protection for hydraulic pumps and significantly extending the service life of equipment;

2. Excellent high-temperature oxidation stability: The rotary oxygen bomb (150°C) test time reaches 432 minutes, which can effectively inhibit the oxidative decay of hydraulic oil under high-temperature operating conditions and extend the oil change interval;

3. Comprehensive operating condition adaptability performance: The copper strip corrosion test reaches Grade 1a, and there is no rust in the liquid-phase rust test under both distilled water and artificial seawater conditions; the demulsification time is only 7 minutes (standard limit ≤ 30 minutes), the air release value is 3 minutes (standard limit ≤ 10 minutes), and the foam characteristic achieves 0 ml residue throughout the process; it still maintains excellent filterability under wet operating conditions, with a dry filtration time of 122 seconds and 144 seconds under 2% water condition, far lower than the standard limit of 600 seconds;

4. Broad base oil compatibility: It can be adapted to Group I and Group II mineral base oils, synthetic base oils, and coal-to-liquids (CTL) base oils, with strong formulation compatibility and high blending flexibility.

Core Applicable Scenarios

(2) Low-Zinc Hydraulic Oil Compound Additive (UNP AH502B)

Core Features of the Formula

Core Performance Advantages

1. Balanced comprehensive performance: wear scar diameter 0.48mm, gear machine test failure level not less than 10, anti-wear performance close to high-zinc products, while rotary oxygen bomb reaching 387min, with excellent oxidation stability;

2. Extreme high-precision filtration performance: Tested according to ISO 13357 standard, the dry oil filtration stage I reaches 95.0%, stage II reaches 93.2%, the filtration stage I under water-containing conditions is 83.8%, and stage II is 65.4%, far exceeding the standard limits. Even when using high-precision filter elements and under water-polluted working conditions, it can still prevent filter element clogging and extend the service life of the filter element;

3. Excellent thermal stability and hydrolytic stability: In the 135°C/168h thermal stability test, the weight loss of the copper rod was only 0.8mg, the weight loss of the steel rod was 1.1mg, and the total sediment was only 4.21mg; in the hydrolytic stability test, the weight loss of the copper sheet was 0.02mg, and the total acidity of the water layer was 0.01mg, far exceeding industry standards, effectively inhibiting oil degradation and sludge formation under high-temperature operating conditions;

4. Excellent fluid performance: Demulsification time is only 5 minutes, air release value is 3 minutes, foam characteristics meet the highest industry requirements, and it can quickly separate water and air from oil, avoiding equipment wear caused by cavitation and emulsification.

Core Applicable Scenarios

(3) Ashless Hydraulic Oil Compound (UNP AH502C)

Core Features of the Formula

Core Performance Advantages

1. Extreme oxidation stability and cleanliness: The ashless antioxidant system has far superior oxidation resistance compared to zinc-containing systems, which can significantly extend the service life of the oil under high-temperature conditions, reduce the formation of sludge, gum, and other deposits, and also has excellent desulfurization ability, ensuring long-term cleanliness of the oil;

2. No risk of metal precipitation: Completely free of metal components such as zinc, no metal salt precipitates will be generated during use, and even long-term use will not cause blockage or jamming of precision valve groups, meeting the core requirements of high-precision hydraulic systems;

3. Comprehensive protection and compatibility performance: It has excellent anti-rust and anti-corrosion protection capabilities for both ferrous and non-ferrous metals, while also exhibiting excellent anti-emulsification and air release performance; it is compatible with mineral base oils and synthetic base oils, and in addition to conventional hydraulic oils, it can also be used in the formulation of anti-wear compressor oils, with anti-wear performance comparable to high-quality mineral oils and PAO/PAO-ester synthetic oil systems;

4. Excellent high-precision filtration performance: There are no difficult-to-filter metal salt products, and even in filter element systems with a precision of 3μm and below, it can still maintain an extremely low filtration differential pressure, significantly reducing the frequency of filter element replacement and operation and maintenance costs.

Core Applicable Scenarios

3. Why is high-zinc hydraulic oil compound additive preferred under high-pressure conditions?

(1) Core pain points of the high-pressure hydraulic system under operating conditions

1. Extremely high contact stress and boundary lubrication risk: Under high-pressure conditions, the friction pairs of hydraulic pumps (mainly piston pumps and gear pumps) will bear extremely high contact stress, and the oil film is extremely prone to rupture. The friction pairs enter the boundary lubrication state, requiring additives to have extremely strong extreme pressure and anti-wear properties, capable of quickly forming a high-strength protective film on the metal surface to prevent scuffing, wear, and pump body failure caused by direct metal contact;

2. Harsh high-temperature operating environment: Under high-pressure conditions, hydraulic oil generates a large amount of heat due to medium compression and mechanical friction. The oil temperature remains at 60-90°C for a long time, and the instantaneous temperature can exceed 100°C, posing extremely high requirements for the oxidation stability and thermal stability of the oil. Oxidation and decay of the oil can directly lead to the loss of anti-wear performance and equipment corrosion;

3. Frequent impact loads and variable operating conditions: Most high-pressure and heavy-duty equipment faces sudden impact loads and variable operating conditions, requiring lubricants to have sufficient anti-wear reserves to meet the lubrication protection needs under instantaneous overload conditions;

4. Complex pollution conditions: Outdoor high-voltage equipment is highly susceptible to contamination by pollutants such as moisture and dust. Water pollution can lead to hydrolysis and failure of additives, oil emulsification, and reduced filterability, which in turn can cause problems such as equipment wear and filter element clogging.

(2) Core Advantages of High-Zinc Hydraulic Oil Compound Adapted to High-Pressure Working Conditions

1. Irreplaceable boundary lubrication anti-wear and extreme pressure load-carrying capacity

2. Excellent high-temperature oxidation stability, suitable for high-pressure and high-temperature working conditions

3. Stable performance under polluted conditions, suitable for outdoor high-voltage scenarios

4. Broad base oil compatibility, meeting the production requirements of high-pressure hydraulic oils of different grades

4. Why Precision Equipment Must Use Ashless Hydraulic Oil Compound

(1) Core oil requirements for precision hydraulic equipment

1. Extreme cleanliness requirements: The servo valves and proportional valves equipped in precision hydraulic equipment typically have internal orifice diameters of only a few dozen micrometers. Even a very small amount of sediment or metallic salt impurities can cause valve blockage, jamming, reduced control accuracy, and even lead to unplanned equipment shutdowns;

2. Ultra-high control precision and stability: The pressure and Byte Flow Control precision of the precision hydraulic system can reach the 0.1% level. Any performance fluctuations in the oil or the presence of contaminants will directly affect the control precision of the equipment, leading to unqualified product processing and interruption of the production process;

3. Ultra-long oil stability requirements: Most precision equipment operates in an indoor constant temperature environment, with oil change intervals typically lasting several years, placing extremely high demands on the long-term oxidation stability and sludge resistance of the oil;

4. Environmental protection requirements of low sediment and low pollution: Some precision equipment is used in industries with high cleanliness requirements such as food, medicine, and electronics, which have strict mandatory requirements for the ashless nature and environmental emissions of oil products.

(2) Core drawbacks of zinc-containing systems in precision equipment

(3) Core Advantages of Ashless Hydraulic Oil Compound Adapted to Precision Equipment

1. Fully ashless formulation eliminates the risk of metal salt precipitation at the source

2. Excellent oxidation stability, meeting the requirements of ultra-long oil change intervals

3. Excellent high-precision filtering performance reduces operation and maintenance costs

4. Comprehensive protection performance, suitable for the diverse needs of precision equipment

5. How to Determine the Zinc Content Plan Based on Equipment During Procurement

(1) The first step in model selection: comprehensively verify the core parameters of the equipment and the original factory's oil usage specifications

1. Hydraulic oil implementation standards recommended by the original manufacturer: Specific standards such as national standards, European standards, and American standards required by the equipment, as well as whether specific pump manufacturer certifications are required, need to be clearly defined. For example, for equipment requiring Denison HF-0 certification, low-zinc type UNP AH502B should be preferentially selected; for equipment explicitly prohibited from using zinc-containing oils, ashless type UNP AH502C must be selected; for equipment requiring high-pressure heavy-duty certification, high-zinc type UNP AH502A should be preferentially selected;

2. Core component types of hydraulic systems: Heavy-duty systems with piston pumps or gear pumps as the pump body have higher requirements for extreme pressure and anti-wear performance, so high-zinc products should be prioritized; systems equipped with servo valves or proportional valves must choose ashless products; medium and high-pressure systems mainly using vane pumps can choose low-zinc products;

3. Equipment rated working pressure: For high-pressure heavy-duty systems with rated working pressure ≥21 MPa, high-zinc products are preferred; for medium-pressure systems with rated working pressure between 10-21 MPa, low-zinc products can be selected; for low-pressure precision systems with rated working pressure ≤10 MPa, ashless products are preferred;

4. Original equipment manufacturers' clear requirements for zinc content: Some imported equipment will clearly specify the zinc content range of lubricants, and corresponding products must be selected strictly in accordance with the requirements. Selection beyond the specified range is prohibited.

(2) Step 2 of model selection: Sort out the actual operating conditions and match the performance advantages of the product

1. Load type: For equipment subject to long-term heavy loads and frequent impact loads, such as mining machinery, metallurgical equipment, and large construction machinery, high-zinc type UNP AH502A is preferred, leveraging its high anti-wear reserve to handle extreme working conditions; for continuous operation industrial equipment with stable loads and medium to light loads, low-zinc type UNP AH502B can be selected to balance performance and cost;

2. Operating Temperature: For high-temperature operating equipment where the oil temperature exceeds 80°C for a long time, the ashless type UNP AH502C with the best oxidation stability is preferred, followed by the high-zinc type UNP AH502A;

3. Environmental Conditions: For outdoor operations and equipment prone to water and dust contamination, high-zinc type UNP AH502A or low-zinc type UNP AH502B with excellent anti-emulsification and hydrolysis stability are preferred; for precision equipment in indoor clean environments, ashless type UNP AH502C is preferred;

4. Oil change interval requirements: For equipment requiring an ultra-long oil change interval, ashless UNP AH502C is the preferred choice, followed by high-zinc UNP AH502A.

(3) Step 3 of model selection: clarify compliance and environmental protection requirements to avoid model selection risks

1. Industry Standards: Equipment in the food and pharmaceutical industries must comply with relevant food-grade lubrication standards, with ashless products being preferred; the electronics manufacturing and precision machining industries have mandatory requirements for oil cleanliness and must choose ashless products;

2. Environmental emission requirements: In scenarios where the local area has strict restrictions on the discharge of zinc-containing wastewater and waste oil, ashless products should be prioritized to reduce environmental treatment costs;

3. Downstream customer requirements: If the produced hydraulic oil products are supplied to customers in specific industries, the corresponding compound additives must be selected strictly in accordance with the customer's zinc content requirements.

(4) Selection Decision Matrix and Avoidance of Common Pitfalls

Decision Matrix for Zinc Content Scheme Selection of Hydraulic Oil Compound Additive

Common Mistakes and Precautions in Model Selection

1. Avoid the misconception that "the higher the zinc content, the better the performance": The zinc content needs to be precisely matched to the operating conditions. Using high-zinc products in precision equipment may instead lead to valve blockage and increase the risk of equipment failure; using high-zinc products in low-pressure operating conditions will result in unnecessary cost waste.

2. Avoid the misunderstanding that "ashless products have inferior anti-wear performance compared to zinc-containing products": Ashless compound additives optimized through formulation, such as UNP AH502C, can fully meet the requirements of medium and low pressure, and even some medium and high pressure operating conditions. Only under extreme high pressure and heavy load conditions do high-zinc systems have more advantages in extreme pressure load-bearing capacity and cost-effectiveness.

3. Avoid the misconception that "the higher the dosage, the better the performance": The dosage of the compound agent must be strictly implemented within the recommended range of the product TDS. Excessive addition not only increases costs but may also disrupt the synergistic effect of the formulation, leading to a decline in performance such as anti-emulsification, defoaming, and filterability.

4. Compatibility test requirements: All three products have excellent base oil compatibility, but during formulation, it is necessary to pre-test the solubility of the compound additive in the base oil and its compatibility with other functional additives to ensure that the performance of the final oil product meets the standards.

5. Performance verification requirements: After model selection is completed, the oil must be formulated according to the recommended formula, and a full range of performance tests must be conducted in accordance with the corresponding national standards and equipment certification standards. Only after ensuring that the oil meets all performance requirements can mass production and use proceed.

Summary

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