E-Zine February 2016

Click here to read “Working with Vendors: Potential Conflict”
Click here to read “Working with Vendors: Mutual Respect”

As discussed last month, if we recognize that the vendor’s technical people know more about the product than the user and the user knows more about the process than the vendor’s technical people, we can move quickly to a professional relationship of mutual respect and trust by following some simple rules.

For the user:

1. Be honest. If you are absolutely honest with the vendor, you will get the vendor’s attention and his or her respect.
2. Provide all the details. If you want competent and quick applications assistance, and help specifying a product, make sure you tell the vendor everything you know about the process so that the vendor can sort them out.
3. Provide adequate time for the vendor to respond.
4. Tell the vendor what the rules are. If you are the decision maker, say so. If you are not the decision maker, make sure the vendor knows who will be making the decisions, and on what basis the purchase decisions will go forward. There is nothing more frustrating than to spend several months working on a project design and then find out that the real purchaser has never heard of you, nor seen the contribution you made to the project. (Translation: lost order, angry vendor and loss of respect and trust of the user by the vendor.)

For the vendor:

1. Make sure you know the rules up front. Spend the time asking about the project, its goals, its direction and who is in charge. If the user won’t tell you, spend your time working with those who will.
2. Approach the “selling” side of a project by deliberately trying to disqualify the user or customer. Let the user trust that control of the project rests with them.
3. Be ruthlessly honest with the customer. If you know of a better solution that you don’t sell, cut your losses and say so. This builds trust and respect.
4. Work with users who guarantee that if you meet all the conditions of satisfaction, you’ll get the order.

Once you’ve developed a relationship of mutual respect and trust, both the user and the vendor can work closely together to get as much value out of the relationship as they put into it.

From Flow Control (March 2002)

'Do Not Bump' - Signs of Just How Much Safety Systems Have Evolved Over the Years

By David W. Spitzer

E-Zine March 2016

There are things that you just cannot forget such as occurred during my visit to a nitration plant that produced di-nitro toluene (DNT). My understanding was that the reactor would produce tri-nitro toluene (TNT) if nitric acid was added in excess. TNT is dynamite so the implication was that the plant would blow up if too much nitric acid was used. Needless to say, this part of the plant was only frequented by people who worked in the unit and needed to be there. Simply put, most plant people simply avoided the unit like the plague.

The reason for my visit must have been a good one albeit long forgotten. The plant was dark, drab and considered antiquated at that time (30 years ago). The instrumentation was largely pneumatic. Orifice plates, variable area, and target flowmeters were commonly used to measure flow at the time.

The one image that I still remember from my visit was looking across a walkway at a variable area flowmeter with a large sign that read --- DO NOT BUMP. My guess is that this (scary) sign was put up as a result of someone or something bumping the flowmeter so as to cause the flowmeter output, controller input, controller output, and valve position to oscillate --- in effect causing the flow to oscillate.

This particular flowmeter may or may not have been the nitric acid flowmeter. There is a high probability that it was not. Nonetheless, it apparently caused a problem for someone and presents us with a reminder of how much safety systems have matured over the decades. It can also cause us to pause and consider making a swift exit.

From Flow Control

Which Flowmeters Aren't Affected by the Upstream Velocity Profile?

By David W. Spitzer

E-Zine March 2016

A. Coriolis mass
B. Magnetic
C. Orifice plate
D. Parshall flume
E. Positive displacement

Commentary
One could opine that all flowmeters are affected by their upstream velocity profile because extreme velocity distortion such as localized jetting could adversely affect any flowmeter. In this case, there would be no correct answer.

Magnetic flowmeter manufacturers publish installation instructions which generally include straight run requirements. Similarly, orifice plate flowmeter standards also specify straight run requirements for accurate measurement and sometimes relaxed straight run requirements for reduced accuracy. These flowmeters can be affected by velocity profile so Answers B and C are not correct.

Parshall flume level measurements can be affected by non-uniform flow such as when there is more flow in the center of the channel, the liquid has waves, or the liquid sloshes from side to side. Answer D is not correct.

As a practical matter, Coriolis mass flowmeters and positive displacement flowmeters are not affected by upstream velocity profile in the overwhelming number of actual installations. Answers A and E would be correct.

Additional Complicating Factors
Most manufacturers publish straight run requirements for their magnetic flowmeters. However a few magnetic flowmeters are designed to have no straight run requirements so they would not be affected by their upstream velocity profile.

Some older Coriolis mass flowmeter designs specified installation of straight pipe upstream and downstream of the flowmeter. While having the appearance of straight run, this requirement was intended to address vibration issues by providing appropriate supports.

ISSN 1538-5280