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MRO Stop Blog

  • Dents on Liquid Filters

    Dents on your filter may result in a cracked filter. These dents often come from an improper installation. Filters with dents should not be used, and filters dented after installation should be replaced as soon as possible. The cost of replacing a dented filter pales in comparison to the cost of any damages that could come out of a dented filter that fails while in use.

    Dents on Liquid Filters
    *Image courtesy of the Donaldson Hydraulic Filtration Product Guide

    Stress on filters often results from pressure pulses in the system. Pressure is regulated by a pressure regulating valve. This valve is spring operated and intermittently opens and closes to regulate pressure. Once pressure goes beyond the setting of the spring in the regulating valve, the valve will open and allow the liquid to flow through until the pressure is alleviated and the spring can expand to close the valve. This process is repeated without pause while the system is in use, creating a pulsing effect. Filter canisters are subjected to the same pulsation. However, unlike the spring in the pressure regulating valve, canister material is susceptible to failure after such fatigue.

    Filters are designed with a low carbon steel to resist fatigue and are formed so the stress created by the pulses in the system are equalized over the surface area of the canister. A dent provides an area of stress concentration where pressure pulses can greatly shorten the fatigue life of the canister.

    *Image courtesy of the Donaldson Hydraulic Filtration Product Guide

  • How Big is a Micron

    The Beta Rating System

    A beta ratio (symbolized by the Greek letter β) is a formula that is used to calculate the filtration efficiency of a particular fluid filter by using base data obtained from multi-pass testing. The purpose of a multi-pass test is to have a lab based procedure that will give one reproducible data that can be used to evaluate the efficiency of hydraulic filters. In a multi-pass test, fluid is continuously injected with a uniform amount of contaminant then pumped through the filter unit being tested. Filter efficiency is determined by monitoring the fluid contamination levels upstream and the contamination levels downstream of the test filter at specific times. An automatic particle counter is used to determine the contamination level. Through this process an upstream to downstream particle count ratio is developed, known as the beta ratio.

    The formula used to calculate the beta ratio is: Beta ratio(x)= particle count in the upstream fluid
    Where (x) is a given particle size

    For example: β10(c)=1000 represents that there are 1000 times more particles upstream than particles downstream that are 10µm or larger. The (c) indicates that the testing was done with APC’s calibrated with NIST fluid.

    Beta stability is the measurement of how well a filter is able to hold up its measured beta ratio when the pressure drops below normal standards. Ex: beta 200 stability=210 psid means that the beta ratio will not fall below 200 until it reaches 210 psid.

    How large is a micron?

    It is difficult to put the measurements and data one gets from the Beta rating system in perspective, particularly when the most of the particles are smaller than a grain of salt. The unit of measurement for these tiny objects, white blood cells, bacteria, and silt being just a few of these things, is often a micron. One micron is .0001 centimeter, or .001 millimeter. In fact, 40µm is the lower limit of visibility, any object that is smaller a person can’t see without the help of a microscope. Keeping all this in mind, it is easy to see how most people don’t really understand how miniscule objects measured in microns really are.

    A Chart of the Micron Sizes of Familiar Particles

    Screen Shot 2016-08-08 at 2.26.23 PM

    *Image courtesy of the Donaldson Hydraulic Filtration Product Guide
    A Grain of table salt: 100µm
    A Strand of Human hair: 80µm
    A Pin Point: 75µm
    The Lower limit of visibility: 40µm
    A White blood cell: 25µm
    Talcum powder: 10µm
    A Red blood cell: 8µm
    Can be felt with a fingertip: 5µm
    A Grain of Silt: <5µm
    The Smallest Bacteria: 2µm

  • Parker's XTR Coating more than 7 times SAE Standard Protection

    Parker XTR Coated Fittings

    A popular option for Parker Tube Fittings and Hose Fittings is their new corrosion resistant coating. It is called out in the part number with the suffix “-ZJ”. The -ZJ designation calls out Parker's XTR coating for extreme corrosion resistance. This coating provides over 7 times the SAE standard. The -ZJ XTR (Extreme Resistance) coating has been tested to withstand corrosion for more than 720 hours where the SAE standard is only 96 hours. Parker's XTR coating is compliant with environmental restrictions worldwide, including RoHS, ELV and REACH.

    Key Values of the XTR Coating

  • Product meets or exceeds SAE J514 and J1453 requirements
  • Enhanced coating extends the life of the connection
  • Additional OEM plant space is gained as secondary paint lines can be removed
  • Increased OEM throughput as plating is already complete
  • Testing Shows Parker XTR Coating Provides Extreme Resistance to Corrosion

    Parker XTR SAE Standards 1Parker XTR SAE Standards 2

  • Parker Fittings Explained: Vibra Seal

    Vibra Seal is a factory applied pipe sealant for tapered pipe threads. It is a tough, non-hardening sealant engineered to be pre-applied to parts.

    Adding VS as a prefix to a Parker Brass Division part number adds the Vibra Seal option. For example, a 1204P-4 90 Degree Male Elbow, 1/4" NPT Male x 1/4" Male, with the Vibra Seal option becomes part number VS1204P-4. A 216P-4 Hex Nipple, 1/4" NPT Male x 1/4" Male, with the Vibra Seal option becomes part number VS216P-4.

    Adding VS as a suffix to a Parker Tube Fitting or Hose Division part number adds the Vibra Seal option. Most fittings that are available with the Vibra Seal option are not stocked, so lead times can be several weeks. In cases where waiting isn’t an option, a standard fitting may be substituted with a liquid thread sealant applied in the field.

  • Donaldson Off Road Mufflers

    Donaldson off-road mufflers come in a variety of styles for off-road equipment. You may be using an standard muffler with your current application but Donaldson invites to check out these mufflers because they are engineered specifically for an off-road application. These mufflers are newer, painted, aluminized steel mufflers have some unique features as compared to the standard line.

    Donaldson Off Road Mufflers Features

  • High Temperature Black Finish
  • Mount or Install in any position
  • aluminized Steel Construction
  • All Have Round Bodies with Domed Ends
  • Slotted Inlet / Outlets Connections

  • Muffler Style 1 End Inlet / End Outlet/ On CenterDonaldson Off Road Mufflers Style 1
    Links to Product Page

    Muffler Style 2 End Inlet / End Outlet/ OffsetDonaldson Off Road Muffler Style2
    Links to Product Page

    Muffler Style 3 Side Inlet / End OutletDonaldson Off Road Muffler Style3
    Links to Product Page

    Muffler Style 4 End Inlet / Side OutletDonaldson Off Road Muffler Style4
    Links to Product Page

    Muffler Style 5 Inlet & Outlet on Same EndDonaldson Off Road Muffler Style5
    Links to Product Page

    Muffler Style 6 Side Inlet / Side Outlet Donaldson Off Road Muffler Style6
    Links to Product Page *Complete Specifications on Product Pages

  • Donaldson Air Ram Inlet Hoods

    Donaldson Air Ram Inlet Hood -Low ProfileDonaldson Air Ram Inlet Hoods with Louvers

    Donaldson Air Ram Inlet Hoods

    • Primarily over-highway trucks
    • For engine airflow of 700 to 1000+ cfm
    • Improves intake system airflow and fuel economy by reducing restriction
    • Lightweight, non-corrosive, and durable
    • Inlet screen prevents large debris from entering intake ducting
    • Side louvers ensure continuous airflow to intake system
    • Common inlet sizes fit most installations
    • Eliminates water from air intake system
    - at 700 cfm airflow = 90%
    - at 800 cfm airflow = 93%
    - at 1000 cfm airflow = 93%*

    Donaldson Air Ram Inlet Hood Diagram

    How Donaldson Air Ram™ Works

    1- Moisture-filled air enters Air Ram.
    2- Air is naturally forced against rear wall. Moisture sticks to the wall, separating from the air.
    3- Moisture collects on the Air Ram wall and drains down to and out of the drain hole.
    4- Virtually moisture-free air passes into air cleaner.

    Air Ram Installation Note

    All Air Ram inlet hoods MUST be installed with the screen facing forward to ensure best performance. Airflow restriction will not be reduced if the Air Ram faces sideways; but if it faces backwards, restriction does increase and adversely affects engine performance.

    Air Ram Inlet Hood Models with Louvers on Side

    (Links to Product)

    Air Ram Inlet Hood Models with Louvers on Side

    (Links to Product)

  • Minnesota Declares June 24th Donaldson Company Day

    Donaldson Company celebrated its hundredth year in business today at their global headquarters in Bloomington, MN. After 100 years of success Donaldson can now add a Minnesota state holiday to their long list of achievements. Mark Dayton, Governor of Minnesota, has officially declared June 24th 2015 as Donaldson Company Day.

    Started in 1915, Donaldson Company began when Frank Donaldson, SR invented an air cleaner for an engine in a local customer’s farm tractor. Since then they have dedicated themselves to the pursuit of innovative solutions to air and liquid filtration. MRO Stop is proud to be a distributor of Donaldson’s filtration products and is excited to contribute to their continued success.
    See Our Donaldson inventory Here

  • 3 Reasons For A Preventative Maintenance Plan

    Preventative Maintenance Plans are crucial to all applications

    Especially when that application is the cornerstone of the company’s profit flow. Disruptions and downtime can be extremely expensive and riddled with disaster. The good news is that a majority that the proper preventative maintenance strategy can eliminate downtime and profit loss.


    When you have a plan for handling errors and problems in production you can perform quick turn around that keeps your production flow going. This efficiency also includes your personnel ability to work on more important things instead of scrambling to get something fixed. Attempting to fix a problem without a plan can take considerably more time than you think.

    Reduced Costs

    Ordering parts in a rush can incur larger shipping costs and that’s if you even order the right part. Waiting for a problem to appear before planning to fix it can mean an overlap in application knowledge and require your personnel to make decisions, under stress, about areas that they aren’t prepared to make. If you have the product on the shelf with an understanding across personnel as to what happens during downtime can really affect the bottom line.


    A preventative maintenance plan means you are actively paying attention to your systems and any potential weaknesses. This adds value by extending the life of your machines instead of letting them just kind of ‘break if they break’. This wastes company resources through both products and personnel. Trained staff is a positive investment overall.

  • Types of Hydraulic Fluids


    Petroleum Based

    Petroleum based fluids are by far the most popular and widely used fluids in hydraulic systems today. It’s popularity can be attributed to its economical pricing and its above average lubricity. Another strong point for petroleum-based fluids are that they have low toxicity levels. Petroleum based fluids can refer to either straight oil or an oil that’s mixed with assorted additives.

    Fire Resistant Fluids

    These fluids are comprised of a high content of noncombustible material, thus giving them their fire resistant ability. These fluids are best used in applications where a host failure or bust could lead to a potentially flammable situation. These fluids are typically divided into two categories Phosphate Esters and High Water Based Fluids.

    HFD Fluids

    HFD fluids are traditional synthetic products that typically don’t contain either water or petroleum. The most common HFD fluid is polyol ester because of its wide range of compatibility with most system materials and it’s amazing fluid performance. HFD tend to be more environmentally friendly that the petroleum and fire resistant fluids because of the absence of certain additives.


    Leaks and accidents can happen at any time and run the risk of hydraulic fluids contaminating the surrounding environment. This is especially as issue with applications near water sources and fragile ecosystems. Biodegradable hydraulic fluids have seen much popularity in the last few years due to the increase regulations around pollution and contamination. Common types of oils are typically vegetable oils and synthetic oils. If you are switching over to a biodegradable fluid from a petroleum based or fire resistant fluid, it’s important to verify that your components are designed to use these fluids.

  • 3 Killer Tips For Hydraulic Filter Storage

    hydraulic filter storage

    1. Filters must be completely sealed during storage

    Otherwise you run the risk of outside contaminants on what should be a brand new clean filter. Metal shelving can cause condensation to form on filters if sitting directly on metal, causing the filter to degrade and rust over time, rendering it useless.

    2. Always handle filters with the utmost care

    Especially if they are not in a box or sealed up. This also pertains to the transportation of filters to and from the job site. Never let filters roll around in the bed or floorboard of a truck.

    3. Utilize the ‘FIFO’ methodology when using filters

    FIFO stands for ‘First In First Out’ , it will serve you well to always use the older inventory first. Make sure filter boxes or containers are properly labeled with dates and information. If you have to pull the filter out every time to see if it is the one you need you are actively increasing the chances of that filter becoming contaminated.

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