Equipment Knowledge Archives | Page 9 of 16

Equipment Knowledge

Who Should Recondition My Seals?

Such a question often comes up when it is time to recondition a mechanical seal: We use several different brands of mechanical seals in my plant. When a pump is taken out of service, we usually send the seal back to the original seal manufacturer for reconditioning. One of my suppliers has offered to recondition all of my seals, regardless of brand. Is this a good idea? Most process plant maintenance departments return their used mechanical seals to the original seal manufacturer (or Seal OEM) for reconditioning.

Equipment Knowledge

What is a valve?

The valve is one of the most basic and indispensable components of our modern technological society. It is essential to virtually all manufacturing processes and every energy production and supply system. Yet it is one of the oldest products known to man, with a history of thousands of years.

Equipment Knowledge

Understanding Shaft Alignment: Basics

Part one of a four-part series that will cover alignment fundamentals and thermal growth, and highlight the importance of field measurements through two case studies. Despite the best efforts to precisely align rotating machinery shafts, dynamic movement (commonly believed to be due to the thermal growth of the machine casings) has resulted in machines operating at less than optimum alignment conditions. This vexing problem has plagued machine reliability professionals for decades.

Equipment Knowledge

Understanding the ‘Diesel Effect’ and How it Damages Hydraulic Cylinders

I was recently engaged by a client to conduct failure analysis on a large (and expensive) double-acting cylinder off a hydraulic excavator. This cylinder had been changed-out due to leaking rod seals after achieving only half of its expected service life. Inspection revealed that apart from the rod seals, which had failed as a result of the ‘diesel effect’, the other parts of the cylinder were in serviceable condition. The diesel effect occurs in a hydraulic cylinder when air is drawn past the rod seals, mixes with the hydraulic fluid and explodes when pressurized.

Equipment Knowledge

The 7 Secrets of Pump Reliability

Contrary to popular opinion, a centrifugal pump is not designed to develop a specific head at a certain capacity as requested by the pump purchaser. In fact a pump is designed and built to produce a whole range of head-capacity conditions as identified by it’s performance curve. The pump will operate on that curve if it is driven at the designated speed.

Equipment Knowledge

The Pump Affinity Laws 2-1

There are occasions when you might want to permanently change the amount of fluid you are pumping, or change the discharge head of a centrifugal pump. There are four ways you could do this, of the four methods the middle two are the only sensible ones. In the following paragraphs we will learn what happens when we change either the pump speed or impeller diameter and as you would guess other characteristics of the pump are going to change along with speed or diameter.

Equipment Knowledge

The Non Seal Pump

Non-leak pumps have been the dream of pump designers ever since the first pump was invented back in the dark ages. We all want a non leaking pump for the obvious reasons. Because of this desire there are a number of companies willing to supply just about any kind of “Voodoo” you are looking for. Let’s take a look at the non seal pump subject and see if this type of pump make sense in your application.

Equipment Knowledge

The Dual Seal Arrangement

Dual seals are recommended for a variety of purposes, but in this paper we will be considering the use of dual seals as an environmental control to prevent the sealed product from either opening the seal faces, or damaging one of the seal components, the two reasons any mechanical seal ever failed.

Equipment Knowledge

The API Gland

The seal gland is that part that holds the stationary half of the mechanical seal and attaches to the stuffing box. The most universally used gland is labeled the American Petroleum Institute (API) gland. The API (American Petroleum Institute) gland incorporates several important environmental controls and safety features. It should be specified for all petroleum refinery service because of the danger of an explosion or fire, but should also be recommended any time you are pumping any type of dangerous product. The gland has several features you need to understand.