Tech Notes, Volume 1, Issue 6
ZN-BASED, ZN-FREE, METAL-FREE OR ASHLESS FLUIDS
We were often asked if any Bel-Ray product, particularly hydraulic fluid, is Zinc-based, Zinc-free, metal-free or ashless. What does that mean?
These fluids typically contain ZDDP. ZDDP is a commonly used name for Zinc Dialkyl DithioPhosphate or Zinc Dithiophosphate. ZDDP is widely used as an anti-wear agent and antioxidant in lubricant formulations. The purpose of anti-wear additives is to maintain lubrication under boundary conditions and help to reduce metal wear. The purpose of antioxidants is to improve thermal stability of lubricants. Chemically, there are many different types of ZDDP. Bel-Ray offers many products that contain ZDDP, such as Raylene Anti-Wear Hydraulic Fluid 00 to 3 (product #71000 to #71080).
Zinc-based fluids could contain additive systems with high zinc (0.07% or greater by weight zinc in the fluid) or low zinc (less than 0.07% by weight zinc in the fluid).
The presence of ZDDP is not always seen as a positive, due to the fact that it can chemically break down and form a viscous, sludge-like product that is difficult to remove and reduces oil filterability. Stabilized ZDDP chemistry has largely overcome these shortcomings, making it an essential additive to the fluid used in any high-pressure, high-performance system, such as those fitted with piston pumps and motors. There also is some suggestion that corrosion problems can arise in contact with certain metal materials with Zinc-based fluid.
Obviously, zinc-free fluids mean oils don’t contain ZDDP additives. Most zinc-free fluids are formulated with ashless additives. However, zinc-free doesn’t mean metal-free. Some metal-based additives are non-zinc-based and formulated into lubricants. Those additives could be calcium-based or other metal-based detergents and molybdenum-based or other metal-based anti-wear agents.
Metal-free or ashless fluids
Metal-free or ashless additives are used in lubricating oils designed to meet anti-wear, anti-rust and anti-oxidation applications and generally provide very good performance. The additives used in ashless fluids are usually phosphorus, sulfur, nitrogen based chemicals.
Metal-free or ashless fluids are excellent choices for applications sensitive to zinc or metals, such as in manufacturing facilities where the waste water is monitored for metal content. Another important advantage of ashless fluids is their ability to operate in fine clearance spool valves where cleanliness is critical. Hydrolytic stability is a problem faced by all systems made from metal as they will inevitably suffer corrosion if exposed to water, even if this water exists as only droplets within oil. While all oils may suffer water ingress through contact with wet air, with coolant ingress or process water contamination, conventional zinc additive oils do tend to suffer more, due to the reaction of the zinc additive and water forming deposits and gels. This is a major concern for filtration, where filter blockages can either cause oil starvation leading to failure of the system or, if oil vents through a relief valve, can deliver unfiltered oil containing contaminants to critical areas.
Despite ashless fluids being generally available for a number of years and despite the fact that their environmental and performance advantages should command serious attention, acceptance levels are still low. It could be that for many engineers the extra cost of ashless oils still outweighs the benefits, especially when price is often the only consideration.
Bel-Ray offers a wide selection of ashless fluids. All Bel-Ray H1 food grade oils are ashless fluids since metal-based additives are not formulated into those lubricants per FDA regulations. Two Raylene products are ashless and multi-grade. They are Raylene Anti Wear Hydraulic Fluid LT-56 (product #71200) and Raylene Multi-Vis Hydraulic Oil 520 (product #71750).
‘O’ ring and ‘X’ ring Motorcycle Chains: What are they and how are they lubricated?
Drive chains for modern ATVs, on-road and off-road motorcycles are available in a standard open pin and bushing chain design and an advanced sealed pin and bushing chain design. Bel-Ray Super Clean Chain Lube and Bel-Ray Blue Tac chain lube address the special needs of the sealed ‘O’ and ‘X’ ring chains. So what is a sealed ‘O’ ring or ‘X’ ring chain and what special needs do they have?
Simply stated, the ‘O’ and X’ designations for a chain refer to the shape of the rubber ring sealing the internal lubrication of a chain. This rubber ring is pressed between the inner and outer sideplates on each side of a chain link. The rings retain the lubricant between the pin and bushing in addition to sealing out dirt and water. This internal lubrication is essential to the chain’s efficiency by keeping the friction between working surfaces to a minimum.
The ‘O’ ring and ‘X’ ring both provide a means of sealing lubricant in the pin and bushing area while keeping contaminants out of the pin and bushing area. The ‘O’ ring does so by squashing the ‘O’ shaped rubber ring between the inner and outer sideplates creating one sealing surface on each contact point. The ‘X’ ring on the other hand creates 2 sealing surfaces on each contact point of the inner and outer sideplates. Chain manufacturers claim that the ‘X’ ring type chain has less friction than an ‘O’ ring chain due to fact that the seals don’t have to be pressed as tight between the sideplates.
To obtain good performance and long life, all chains must always be lubricated when in service. A well lubricated chain keeps the friction between the working surfaces to a minimum by creating a protective surface between the sliding surfaces of the pin and bushing and also between the bushing and roller. Bel-Ray Super Clean Chain Lube and Bel-Ray Blue Tac Chain Lube contain special anit-wear additives that provide exceptional protection against metal to metal contact. A lack of lubrication increases friction between these surfaces which increases the working temperature of the components resulting in a loss of power. This higher than normal temperature will result in the internal lubricant burning away and becoming less effective, therefore increasing chain wear.
In the ‘O’ ring and ‘X’ ring chains, lubrication is provided by the sealed grease between the inner and outer sideplates. However, it is still necessary to provide periodic lubrication to the chain. Lubricant between the roller and bushings will decrease friction and heat. The Super Clean and Blue Tac Chain Lubes protect chain components against shock loading and severe wear caused by metal-to-metal contact. This will improve the efficiency of the chain extending chain and sprocket life.
The life of a sealed chain is usually determined by the durability of the rubber ‘O’ or ‘X’ ring. To improve the durability, there should be a film of Bel-Ray Super Clean Chain Lube or Bel-Ray Blue Tac Chain Lube on the ‘O’ or ‘X’ ring at all times. Even though it is a sealed chain, lubrication is required to extend the working life of the rubber sealing ring. Lubrication also keeps ‘O’ and ‘X’ rings in good condition and protects the metallic components from rust and corrosion. Rust and corrosion lead to pitting of the metal parts which greatly increases friction which greatly reduces how efficient a chain works. Signs of poor lubrication are rapid elongation of the chain, also rust and squeaking when operating.
External lubrication with Bel-Ray chain lubes is crucial. Chains used in dirty environments require cleaning and lubrication regularly. If the chain is not too dirty, the application of a chain lubricant is sufficient. When the accumulation of dirt on the chain (sand, mud, asphalt particles or other foreign materials) is excessive, the chain must be washed or cleaned with a product such as Bel-Ray Foam Filter Cleaner & Degreaser. Many cleaning sprays contain harsh solvents that cause deterioration of the rubber sealing rings. Do not allow chains to air-dry after washing, or to rust. The chain has to be dried immediately with a jet of compressed air. A coating of Bel-Ray Super Clean Chain Lube or Bel-Ray Blue Tac Chain Lube, which dries quickly can then be applied forming a protective waterproof coating that will not fling off the ‘O’ or ‘X’ ring chain.
In order to properly maintain an advanced ‘O’ ring or ‘X’ ring chain, an external lubricant with unsurpassed anti-wear protection like Bel-Ray Super Clean Chain Lube and Bel-Ray Blue Tac Chain Lube must be used. The performance of a chain will benefit from Bel-Ray’s high performance chain lubricants.
Slow it Down in Cold Weather
There is a common misconception among operators of Lincoln auto lube systems that when the lubricant gets cold, air pressure to the pump should be increased. This practice is not only incorrect, but it can cause catastrophic failure and is a potential for an accident.
The air regulator is used to control pump speed only. System pressure is controlled by the pressure switch and safety unloader. What this means is if air pressure is increased to the pump, the pump runs faster. Conversely, if pressure is decreased to the pump, it runs slower.
Pressure drop is the difference in system pressure at the pump compared to the end of the line pressure at the injectors. This is a result of the lubricant’s resistance to flow in the line. In general in a system, the farther away a location is from the pump, the lower the pressure will be. This is important since injectors, which are at the end of the line, require a minimum of 1850 psi to dispense lubricant. Furthermore, the pressure switch, which regulates maximum line pressure, is often at the opposite end of the supply line from the injectors, near the pump, where line pressure is highest. Therefore, the danger exists when pressure drop is high, for the pressure switch to be satisfied at 2500 psi and have only 1500 psi at the injectors. This will result in no lubricant being dispensed.
When the air pressure to the pump is increased, the amount of pressure drop also increases. This is the result of the pump running faster and generating a great deal of system pressure close by. In a worst-case-scenario, the pump would run so fast that a pressure surge would trip the pressure switch and shut down the system before adequate pressure was generated at the injectors. As a result, the injector would not cycle and dispense any lubricant; components would fail due to the lack of lubrication. Therefore, it is best for the pump to operate slowly to minimize pressure drop.
As weather gets colder, lubricants become stiffer, increasing line resistance which increases the probability of increased pressure drop. When it is cold, it is very important that air pressure not be increased, in fact, it is often helpful to turn it down. 60 psi air pressure is recommended for 75:1 pumps (4500 psi systems) and 80 psi is recommended for 50:1 pumps (4000 psi systems).
However, some of Bel-Ray’s heavier lubricants like Molylube Gear Tac, Molylube SF 100 and Molylube 87M EP Grease are hard to pump at low air pressure. In this situation, the pump can be run at a higher air pressure if the air inlet fittings are restricted (“bushed down”) to restrict the flow of air. This will maintain a slow pumping rate. Delay fault time may need to be extended to give lubricant time to move without setting off system alarms. Pressure switch settings may need to be increased. Regardless of air pressure setting, it is always important to monitor injector operation in cold weather.