Open impellers are frequently used in centrifugal pumps which pump liquids that contain suspended solid materials (slurries, paper stock, etc). They do not plug as easily as closed impellers and usually have a simple external adjustment to maintain the correct impeller clearance as internal parts wear.

In theory, machine alignment is a straightforward process, but in real world applications, it is often compounded by structural faults such as ‘soft foot’, piping strain, induced frame distortion, excessive bearing clearance or shaft rubs. These pitfalls can turn a simple job into an all day affair – frequently with unsatisfactory results despite a conscientious effort and a considerable investment in manpower and downtime. This paper will examine how to eliminate some of the typical reasons why alignments are unsuccessful.

What is electrical corona? Corona is the ionization of the nitrogen in the air, caused by an intense electrical field. Electrical corona can be distinguished from arcing in that corona starts and stops at essentially the same voltage and is invisible during the day and requires darkness to see at night. Arcing starts at a voltage and stops at a voltage about 50% lower and is visible to the naked eye day or night if the gap is large enough (about 5/8″ at 3500 volts).

Regardless of the approach taken to measure true dynamic movement, coupled machines need to be set to cold alignment targets that will reflect the actual changes in the shaft alignment. This will lead to lower vibration levels, increased Mean Time Between Failures, decreased maintenance expenditures and increases in production. Much like the philosophical change from aligning shafts with dial indicators to aligning shafts with laser based systems, these types of measurements will take some time to be generally accepted and routinely practiced.

Mass unbalance in a rotating system often produces excessive synchronous forces that reduce the life span of various mechanical elements. Unbalance is basically very simple case caused by an asymmetry in the rotating element that results in an offset between the shaft centerline and center of mass. Asymmetry can be an off-center weight distribution, or it can be a thermal mechanism that produces uneven heating and bowing of the rotor, or it can be an electrical effect that produces uneven magnetic field.

Machinery can be idle from intermittent use, stand-by (redundancy), storage for spare parts, or for temporary decommissioning. This article looks at practices that protect equipment characterized as decommissioned, short-term storage or storage of stand-by capacity.

For many applications, a REFRIGERATED COMPRESSED AIR DRYER is one of your best solutions to getting the moisture out of your compressed air system. Look for these symptoms to tell when you need a Refrigerated Compressed Air Dryer…

There has always been a debate on whether jack screws should remain tight against the side of the machine case after the machine has been moved into position or to back off the screws, so they do not touch. Should jack screws be tight or backed off? The answer is yes and no. In some situations you should leave the bolts tight against the machine and in other situations, it may be better to back off the jack screws.

“What’s the system’s normal operating temperature? What’s the system’s usual operating pressure range?” If you can’t answer these two basic questions about the vital signs of your hydraulic equipment I strongly recommend you make the effort to get to know your hydraulic equipment better. The information is easy to collect and can give valuable insight to the health of your hydraulic equipment.