Recent Blogs Posts

1. My Personal Safety Quotes:

by , 05-27-2013 at 12:07 PM
Over the years I have come up with several of my own safety and leadership quotations that I have used either in conferences, meetings or training sessions. Sometimes you can say just a few words and the message sticks with people for the rest of their lives. I have put below a few of my favourites that I have had success with when trying to make people accept their responsibilities and become leaders. Hopefully people will find useful to use during their own HSE or OHS training etc.

"Good leaders are those who know how to motivate and challenge people at all levels of an organization to achieve their best performance. In addition they support and provide the resources necessary to ensure it is possible to meet the goals that have been set”.

“No one cares how much you know about safety, until they know you can add to their success”

“ If you want to be a safety leader you must have innovation to succeed”

“I may not be a financial director, but I can help reduce your financial loss”

“If you don’t consider safety part of your leadership strategy, then you’re in the wrong job”

“A company director who thinks safety is a costly overhead should resign at the first opportunity”

“Only a fool would take a risk that would lose money or cause personal injury”

“You can’t say cutback on safety, and build a successful business in the same sentence”

“Real leaders know when to motivate and when to stand up for change”

Wayne Harris
Chairman of ISQEM

www.isqem.com
2. PSV sizing with HEM (Homogeneous Equilibrium Model), limits of application

by , 04-17-2013 at 11:32 AM

Prode Properties allows to size / rate a PSV for critical or two-phase flows with different models including HEM (Homogeneous Equilibrium Model)
The HEM model for the nozzle applied in Prode Properties solves

hin+1/2*vin^2 = ho+1/2*vo^2

(in = inlet, o = orifice)
where vo (for a critical flow) is the speed of sound
ho, vo calculated at vena contracta conditions

this model works well for critical and two-phase flows,
it is also applicable for subcritical flows within certain limits.
For subcritical flows Prode calculates the area solving a constant energy operation but since usually for a nozzle we do not specify the internal area of pipe (which is required for calculating vin in above formula the procedure estimates the value, this may generate errors when the rate vo/vin is low.
For such cases it is suggested to use as alternative to ISPF() the method EPF

double t = EPF(integer stream, double p, double E, double aout, double et)

this method allows to specify both inlet and outlet condition thus modeling a adiabatic, irreversible expansions when the contribute of kinetic energy cannot be neglected.
Tags: hem, nozzle, psv, safety, sizing
Categories
Uncategorized