I looked up Applied Technology (by Garry Cruickshank and Peter Shapcott)
from unitec and it states natural gas having 5% LEL 14% UEL

and the 2003 exam states it having           5% LEL 15% UEL

The same book mentioned above states Natural gas having a heat value of 40MJ/m3 and LPG having a heat value of 102 MJ/m3.

But when looking into NZS 5261 on page 137 you will find NG HHV 38 and LPG HHV 96.

The little footnote under the graph states " These graphs give adequate results for gases whose higher value and relative density are within +/- 15% of these values."

You can see how this statement could also apply when it comes to the UEL and LEL of a gas.

If your not sure what value to use, you could always note the range for example. LPG 1.6%-2.5% LEL and 7.8%-10% UEL.

hope that helps.

Please note that the advice I am giving is only my opinion and not necessarily a fact. Plumbers.co.nz will not take any responsibility for applying advice from this forum. Please refer to our terms and conditions.


                                                                                                         

To anyone sitting plumbing registration exams i reccomend studying the following in order of importance;

1. Remember all the answers to previous exams word for word, particularly exams from 3-5 years prior.
2. Read Doyles book 1 sections Safety, Trade Science, and Welding and all of Doyles book 2 numerous times to gain a good overview of some of the more less known parts of plumbing.
3. Download and remember the objectives, functional requirements and performance criteria (on the second page) and the definitions of the codes E1, E2, B1, B2, G12, G13. Exams have heaps of definitions from these codes.
4. Study G12 and G13, remember measurements of wastes, vents and pipe sizes, supports etc. Remember everything about hot water cylinders and systems. Get new G12 with solar section (could be in upcoming exams).
5. Study the Act and licensing information from the PGDB website.
6. Study As3500 but only to get an understanding, often specific details are not included in the exam. The BRANZ book is excellent for this.
7. Practise technical drawing (Unitec module) and equations. Also practise drawings from previous exams.+
8. Print out previous exams and practise sitting them (close to exam time) after you have studied and remembered the answers. Writing the answers down will help.

Start studying a few months before the exam at least twice a week. Get all your study materials together first and write down what you are going to study and when you will study. Get a couple of exercise books and take brief notes of what you think is important. Do the refresher course at UNITEC but only as a final preparation, the real study should happen long before that. Success doesn't depend on how smart you are but how many hours you study for. In the last 2 or 3 weeks you should study every night. Hope this helps.

There is actually nothing in the craftsman common exam that will make you a bettter plumber. Its all absolute rubbish. We spent an hour in my last night class learning how to write a sentence and where the nouns and the adjectives go.
The sooner they get rid of this absolute nonsense the better. And how many plumbers out there do air conditioning? There's a large section in the common exam about this and its not even part of our trade.
Its no wonder so many of us are leaving for Australia. This exam is actually ruining the plumbing industry in New Zealand as all the good plumbers get so pissed off they go to oZ and we are left with the immigrants who come here and cant talk English. I spose its good for the big companies though...less Craftsmen out there to compete for their business.