05262017Fri
Last updateThu, 25 May 2017 3pm

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The Future of Coal: Efficiency Over Politics?

The Future of Coal: Efficiency Over Politics?

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Valve World Americas Event Set for June 20-21

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Industry Headlines

Emerson Acquires MYNAH Technologies

1 DAY AGO

Emerson has completed the purchase of MYNAH Technologies, a long-time Emerson alliance partner. The addition of MYNAH will help support Emerson Automation Solutions and its Operational Certainty program. Terms of  the acquisition were not disclosed.

MYNAH software is currently in use at more than ...

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Roger Fix Named Chairman of Flowserve

2 DAYS AGO

In its most recent annual meeting, Flowserve announced that Bill Rusnack and Lynn Elsenhans have retired as members of the board of directors. Flowserve also announced that board member Roger Fix has been elected to replace Rusnack as chairman.

"Bill and Lynn provided years of distinguished service to ...

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Oil-Fired Plants Provide Small Amount of U.S. Electric Capacity, Generation

13 HOURS AGO

According to the U.S. Energy Information Administration , roughly 70% of petroleum-fired electric generating capacity that still exists today was constructed prior to 1980. Utility-scale generators that reported petroleum as their primary fuel comprised only 3% of total electric generating capacity at...

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ExxonMobil, SABIC Agree on Proposed Petrochemical Project

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Affiliates of Exxon Mobil and SABIC (Saudi Basic Industries Corporation) signed an agreement to conduct a detailed study of the proposed Gulf Coast Growth Ventures project in Texas and begin planning for front-end engineering and design work. The agreement was signed during the Saudi-US CEO Forum in R...

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Business Borrowing for Capital Investment Up 8% in April

13 HOURS AGO

The Equipment Leasing and Finance Association’s (ELFA) Monthly Leasing and Finance Index, which reports economic activity from 25 companies representing a cross section of the $1 trillion equipment finance sector, showed their overall new business volume for April was $7.9 billion, up 8% year-ov...

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Leading Economic Indicators for the U.S. Increased in April

1 DAY AGO

The Conference Board Leading Economic Index (LEI) for the U.S. increased 0.3% in April to 126.9 (2010 = 100), following a 0.3% increase in March, and a 0.5% increase in February.

“The recent trend in the U.S. LEI, led by the positive outlook of consumers and financial markets, continues to point ...

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Grease for Motor Actuator Maintenance

Maintaining the right amount of grease inside motor actuators that use grease for lubrication is a vital part of valve maintenance, and can save time and money by preventing problems before they happen. Inadequate lubrication is often the culprit in a malfunctioning motor actuator, and understanding how to effectively manage grease in motor actuators can be a simple way to keep costs down and to keep actuators out of the repair shop.

Motor actuators must have the correct amount and type of grease in the gear case to provide for trouble-free operation.

 

Getting Inside
The first step is getting inside the actuator. Actuators have from two to four grease plugs to allow adding and checking the level of grease. The quality, quantity, and consistency of the grease in the actuator should initially be checked every 18 months, then at a frequency derived from the results. This inspection must be accomplished through these grease plugs.

Motor actuators are built to operate on the partial immersion principle. What matters is whether or not the "worm" is totally immersed in grease. This is to ensure that the efficiency of the worm/worm gear set is operating at its highest level, because this gear set is the most inefficient gear set in the actuator, operating at about 20% to 25%.

Due to the heat of the sun or system operation, the gear box is pressurized, which is why just filling up the gear box with grease causes the grease to push through the seals and into the motor windings and/or into the limit switch compartment.

To determine the correct amount of grease to add to a gear box, perform an inspection by using one of the many "fill and drain" plugs to ensure the worm is totally immersed in grease. When the actuator is mounted in a different orientation, the amount of grease needed to totally immerse the worm will change.

If your actuator is disassembled for repairs or rebuilding, these grease plugs should all be removed, cleaned, and reinstalled. Sometimes these plugs will be corroded in the housing and must be drilled out. Due to the metal chips that will fall into the grease, don't drill them out during operation. Instead, remove them during the rebuild when the inside is exposed.

The drive sleeve in an actuator extends through the housing on both the bottom and top sides. A seal is used to prevent leakage of grease at this penetration. The lower drive sleeve is held in place by a seal retainer, which is installed and removed, from the bottom of the actuator. This seal retainer is held in place by screws, bolts, or just a press fit on different sizes of actuators.

When the actuator is disassembled for repair or rebuild, this seal retainer does not need to be removed to fish out the seal and replace it. However, it should be removed to allow the rebuilt drive sleeve to be installed first. If the seal is installed first, and then the drive sleeve, there is no way to ensure that the seal is not nicked or rolled during the drive sleeve installation.

Grease in the main gear box will not flow into the clutch housing compartment of the actuator, so this compartment must also have grease added to cover the motor pinion/worm shaft clutch gear set. Fill this area just enough to cover the gear set-not too full.

The actuator can be mounted in any position since it has a totally sealed gear case. However, mounting positions that would cause vulnerable areas of the actuator (e.g., motor and limit switch compartment) to be saturated with grease in the event of a seal failure are not recommended.

The Right Grease
Use only the correct type when adding grease to your actuators. This means the grease must:

 

  • contain an "EP" additive
  • be suitable for the temperature range needed
  • be water and heat resistant and non-separating
  • not create more than 8% swell in Buna N or Viton seals
  • not contain any grit, abrasive, or fillers
  • not slump-preferred NLGI grade 0 to 1
  • not be corrosive to steel gears, ball, or roller bearings
  • have a dropping point above 316° F for temperature ranges of -20° F to 150° F.

In addition to the above, keep in mind that grease is made up of a filler (soap) and oil. Different types of fillers are used and not all types will mix well with each other. If you are going to add grease, use the same type of grease in the gearbox or ensure the new grease is compatible.

Regularly checking the level and quality of grease inside motor actuators will provide results that speak for themselves. Quite literally, proper lubrication makes a motor actuator function more smoothly, and keeps it lasting longer and working at maximum efficiency at very little cost.

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