7 Type II: High-Pressure Appliances

Appliance scope and pressure categories

Type II certification covers technicians working on medium-, high-, and very-high-pressure appliances. It does not cover small appliances, motor-vehicle air conditioners, or MVAC-like appliances.

A high-pressure appliance uses refrigerant with a liquid-phase saturation pressure of $170\text{–}355\ \mathrm{psia}$ at $104^\circ\mathrm{F}$. Examples include systems using R-22, R-407C, R-410A, and R-502. Very-high-pressure appliances use refrigerants with a critical temperature below $104^\circ\mathrm{F}$ or a saturation pressure above $355\ \mathrm{psia}$ at that temperature.

Recover refrigerant safely

Section 608 prohibits knowingly venting refrigerant during service. Recover refrigerant into an appropriate external container using recovery/recycling equipment certified for both the refrigerant and the appliance, and follow the equipment manufacturer’s instructions. Recovery removes and stores refrigerant; it does not, by itself, clean or reclaim it.

System-dependent recovery equipment relies on the appliance’s own components to move refrigerant. It cannot be used on an appliance with a full charge over $15\ \mathrm{lb}$, unless the equipment is permanently attached as a pump-out unit.

Removing liquid refrigerant first generally speeds recovery. After reaching the required recovery level, pause and check whether system pressure rises; a rise can indicate refrigerant remains in liquid form or dissolved in oil. Use recovery cylinders and equipment rated for the refrigerant, and do not overfill cylinders.

Evacuate before opening

Before opening an appliance for service or disposal, recover the liquid refrigerant and evacuate either the whole appliance or the isolated section being serviced. Vacuum readings below are inches of mercury below atmospheric pressure; atmospheric pressure is stated as $29.9\ \mathrm{in.\ Hg}$. The equipment date means the date it was manufactured or imported.

• Very-high-pressure appliance: Required level is $0\ \mathrm{in.\ Hg}$ vacuum with equipment made before November 15, 1993, and with equipment made on or after that date.

• High-pressure appliance with a charge under $200\ \mathrm{lb}$: Required level is $0\ \mathrm{in.\ Hg}$ vacuum with either equipment date.

• High-pressure appliance with a charge of $200\ \mathrm{lb}$ or more: Required level is $4\ \mathrm{in.\ Hg}$ vacuum with equipment made before November 15, 1993, or $10\ \mathrm{in.\ Hg}$ vacuum with equipment made on or after that date.

For example, a high-pressure appliance charged with $250\ \mathrm{lb}$ requires evacuation to $10\ \mathrm{in.\ Hg}$ vacuum when equipment made on or after November 15, 1993, is used.

Do not confuse these evacuation levels with the special rule for a non-major repair that is not followed by evacuation of refrigerant to the environment: a high- or very-high-pressure appliance must be brought to $0\ \mathrm{psig}$ before it is opened. A major repair includes removing the compressor, condenser, evaporator, or auxiliary heat-exchange coil, or uncovering an opening with a flow area larger than $4\ \mathrm{in}^2$ for more than $15\ \mathrm{minutes}$.

If a leak prevents reaching the required vacuum, isolate leaking sections from non-leaking sections wherever possible. Evacuate non-leaking sections to the required level. Evacuate a leaking section to the lowest level attainable without substantially contaminating the recovered refrigerant, but not above $0\ \mathrm{psig}$.

Detect leaks and meet repair requirements

Leak-test the system before charging or recharging. Excessive superheat or oil traces on a hermetic system may point to a leak. Suitable leak-location methods include electronic detectors and bubbles.

For pressure testing, use regulated nitrogen, not oxygen or compressed air. Use a pressure regulator and relief protection. Nitrogen alone is an appropriate test gas; nitrogen with a trace amount of refrigerant can also help locate leaks when suitable.

A separate EPA leak-repair program applies to appliances with a full charge of $50\ \mathrm{lb}$ or more of ozone-depleting refrigerant: a Class I or II substance, or a blend containing one. It does not apply to appliances containing only substitute refrigerants. The owner or operator must take corrective action when the annualized leak rate exceeds the applicable trigger:

• Industrial process refrigeration: $30\%$.

• Commercial refrigeration: $20\%$.

• Comfort cooling: $10\%$.

• All other appliances: $10\%$.

In general, the owner or operator must repair leaks within $30\ \mathrm{days}$ of discovery, or develop a retrofit or retirement plan within $30\ \mathrm{days}$ and complete it within one year. An industrial-process shutdown can allow a $120$-day repair period. Certain limited extensions may apply.

Repairs under this program require an initial verification test after repair and before refrigerant is added, followed by a test after the appliance returns to normal operating conditions. These regulatory deadlines are distinct from a technician’s duty to follow proper service and recovery practices on any covered appliance.

Other service practices

Use sound recovery practices and equipment suited to the refrigerant, and avoid intentional releases. Recovered refrigerant may be returned to the same system or to another system owned by the same person. If ownership changes, it generally must be reclaimed by an EPA-certified reclaimer before resale or use by the new owner.

Before removing oil, reduce pressure in the appliance or isolated section to no more than $5\ \mathrm{psig}$. Alternatively, drain the oil into a receiver that will be brought to no more than $5\ \mathrm{psig}$, because refrigerant can remain dissolved in oil.

Do not energize a hermetic compressor while the system is under vacuum. Protect against refrigerant exposure, including oxygen displacement and frostbite, and use appropriate procedures and protective equipment.