Bench Degree·REFRIGERATIONchapter

Before You Start

One page. The parts list for the whole volume is Appendix A, at the back of the book; Chapter 1 will tell you what it needs. This page is the part you should not find out later.

Not a disclaimer. Four specific things in this book can actually hurt you, and none of them will if you read this.

Vacuum. A jar that is not rated for vacuum can implode, and it fails inward with glass. Use a purpose-made chamber or a heavy-walled vacuum-rated vessel, and wear eye protection while pumping.

Compressed air dusters. The contents are not air. They are a liquefied refrigerant, they are dangerous to inhale deliberately, and they will cause a cold burn if the can is held against skin for a long discharge. People have died from inhaling these. Use them as described and no other way.

Refrigerant under pressure. A live system holds several hundred kPa (tens of psi) on the low side and well over 2,000 kPa (300 psi) on the high side. Liquid refrigerant escaping onto skin causes an immediate frostbite injury, and into an eye causes permanent damage. Gloves and eye protection whenever a hose is connected or disconnected.

Mains electricity. Every machine in Part VI runs on it, and commercial equipment in Chapter 20 runs on three-phase at 208 V or higher, which is lethal. Nothing in this book requires you to work on a live panel. Where a chapter asks for a current reading, a clamp meter takes it from outside the insulation without contact.

One general rule that covers most of it: do your first attempt at anything on a scrap unit you do not care about. The window air conditioner from the kerbside exists so that the mistakes happen there.

Bench Degree

Get the degree without the diploma.

Learn the material, not how to pass the exam.