MOV Long Life
MOV Long Life and MOV Extra Greases
There is no such thing as a universal grease. Greases can vary in many ways including the base oil viscosity, base oil type, thickener and additives as well as the target cost. Because of this the characteristics and performance can range widely. There are many that can do okay in a variety of uses but there can still be significant cost benefits to have specialty greases suitable for specific applications. This includes essential components. Safety related MOV (motor operated valves) are one such application. The grease must satisfy the requirements of the actuator supplier as well as having the required radiation, temperature and steam/water resistance to continue to be able to perform their design function after a serious event. For example, after a reactor heat transport pipe break. In addition, for both the actuator and the stems the grease must maintain a consistent coefficient of friction to ensure that the bounds are not exceeded and do not impact on the torque switch settings nor cause excessive wear.
For some actuators, the historical grease worked okay, but reportedly had issues with rapid hardening in service. Alternatives were being actively sought by the industry and by EPRI (Electric Power Research Institute). The goals were to find a better grease and one that could be used in all three applications. This is in the actuator gearbox, in the limit switch gearbox and on the threaded valve stems. Fortunately, in 2001 when it was announced that the prior grease was to be discontinued, evaluations had already identified a suitable product. Testing in 2002 confirmed that it was better and, in that year, MOV Long Life became the factory fill for Limitorque SMB actuators. Later work showed it to be suitable for the limit switch gearbox and on the stems. It is also being used by other actuator suppliers.
MOV Long Life is available in NLGI consistency Grades 0,1 & 2 depending on the application. A semifluid product for oil filled actuators was also developed but has not yet been commercialized. In addition, for commercial applications MOV Extra is available. This uses a lower viscosity base oil for better low temperature performance. In addition, the base oil is less refined so available at a lower cost and being commercial, it does not require the QA necessary for nuclear applications.
MOV Long Life is being used around the world and is available from a number of distributors.
MOV Long Life greases tested by EPRI for high temperature MOV’s and for bearings in Lube Notes for December 2006. Both did very well in comparison to the alternatives, especially when all the characteristics were considered.
Note Number 1, High Temperature Grease Evaluation: “The MOV LL result at the stem nut temperature of 85°C (185°F) warrants consideration in future testing. Not only does it appear that it will retain oil better, but it also has better oxidation stability and consistency retention (remaining a grade 2) than the other lubricants evaluated.”
Note Number 3, Comparison of Roller Bearing Greases: “We believe that MOV LL will prove to be superior in antirust based on other, more rigorous tests. This feature is important in areas of high humidity near an ocean. Given that a bearing failure occurred due to a weld seize, there is a comfort in choosing MOV LL that has a significantly higher weld point and load-carrying ability.”
Suppliers Of MOV Long Life And MOV Extra
To order MOV Long Life, MOV Extra or VSG (biodegradable)
Toll Free: (1-855) 520-2020 or (1-905) 820-2022
(800) 536-6070 or (770) 426-6070
Valves & Automation Inc
555 Executive Drive, Willowbrook, IL 60527
* Usually have MOV Long Life Grades 0,1 & 2 in stock as well as
MOV Extra Grades 0 &1
COG (Candu Owners Group)
MUG (Motor Operated Valve Users’ Group)
EPRI (Electric Power Research Institute)