Refrigeration fluid recovery apparatus

An apparatus adapted for recovering compressible refrigeration fluid from a refrigerator means and delivering the recovered fluid under high-pressure conditions along a line to a receptacle, in fluid communication and in sequence along the line. An accumulator means to which refrigeration fluid from the refrigerator means in gaseous form is drawn, a compressor to compress the refrigeration fluid from the accumulator and create a vacuum condition for drawing refrigeration fluid from the refrigerator means, and a condenser to liquify the refrigeration fluid for delivery to the receptacle, the improvement characterized by a secondary receptacle being provided, communicating with the line between the condenser and receptacle and with the line upstream of the accumulator, and a valve means in the line between the secondary receptacle and the compressor arranged, when the pressure in the secondary receptacle exceeds a predetermined value, so that the valve will open to allow some of the refrigeration fluid to flow back to the compressor for recondensation, to thereby lower the pressure in the receptacle.

FIELD OF THE INVENTION 
The present invention relates to an improved apparatus for recovering 
compressible refrigeration fluid from a refrigerator means. 
BACKGROUND OF THE INVENTION 
Apparatus has been developed for recovery of refrigeration fluid 
(refrigerant) from refrigerator systems such as air conditioners, 
refrigerators and the like, for delivering that recovered fluid to a 
receptacle such as a receiving cylinder (high-pressure) or drum 
(low-pressure). Such apparatus conventionally comprises an accumulator 
means to which refrigeration fluid from the refrigerator system is drawn 
in gaseous form. A compressor compresses the refrigerant from the 
accumulator and creates a vacuum condition for drawing refrigerant from 
the refrigerator system. A condenser liquifies the refrigerant from the 
accumulator for delivery of liquid refrigerant to the receptacle. 
A problem with such apparatus is that, under higher temperature conditions 
in particular, the vapor pressure in the receiving cylinder increases to 
the point that either recovery is extremely slow or the recovery equipment 
must be shut down as pressure is too high. As well, the high pressure 
relief on the cylinder may "blow" to atmosphere since the pressure is too 
high. In this latter case, since most conventional refrigeration fluids 
are environmentally hazardous, it is unacceptable and in many 
jurisdictions illegal to have such apparatus which releases such gases to 
the atmosphere. 
Solutions to such problems of high pressure refrigerant recovery apparatus 
have included switching the receiving cylinders (in which case much time 
is consumed and the result is cylinders which may be only partially full), 
waiting for the receiving cylinder to cool down, at which point the 
pressure will be accordingly reduced (again very time consuming) or 
cooling the receiving cylinder with water or ice (ice is seldom available, 
water is usually not available and a bath arrangement is needed in which 
to immerse the receiving cylinder). 
Similar apparatus, used for instance in recovery of refrigeration fluid 
such as R11 (trade-mark) at low pressures, may use drums as the 
receptacles. The drums withstand only very low pressure when operating in 
association with such recovery apparatus. Thus, the vapor pressure in the 
drum must be monitored so that it does not increase to an unacceptable 
level. Again, in the past, venting of the drum to the atmosphere has been 
the conventional solution for reducing the vapor pressure build-up which 
may occur as the drum is being filled with recovered refrigeration fluid. 
U.S. Pat. No. 4,981,020 of Scuderi issued Jan. 1, 1991 describes an 
apparatus for recovering a compressible refrigeration fluid from a 
refrigeration system which includes a safety tank for preventing 
over-filling of the receiver. The safety tank communicates directly with 
the receiver. So long as the safety tank receives refrigerant in the gas 
phase, the apparatus simply passes that refrigerant back to the compressor 
for return to the receiver. If however the receiver is filled, liquid 
refrigerant will pass to the safety tank, activating switches and valves 
to close down the recovery operation, thereby terminating the flow of 
refrigerant to the receiver. This apparatus however does not respond to 
high pressure conditions in the receiver, the safety tank merely being an 
overflow receptacle for liquid once the receiver has been filled. 
Other references of general background interest relating to refrigerant 
recovery apparatus include U.S. Pat. Nos. 5,018,361 of Willikroll et al 
issued May 28, 1991, 5,058,631 of David C. H. Grant issued Oct. 22, 1991, 
5,040,382 of Anthony W. Abraham issued Aug. 20, 1991, 5,038,578 of Manz et 
al issued Aug. 13, 1991, 5,033,271 of Manz et al issued Jul. 23, 1991, 
5,024,061 of Pfeil et al issued Jun. 18, 1991, 4,998,413 of Sato et al 
issued Mar. 12, 1991, 4,938,031 of Manz et al issued Jul. 3, 1990, 
4,903,499 of Thomas D. Merritt issued Feb. 27, 1990, and 4,809,520 of Manz 
et al issued Mar. 7, 1989. 
SUMMARY OF THE INVENTION 
In accordance with the present invention there is provided an improved 
apparatus adapted for recovering compressible refrigeration fluid from a 
refrigerator means and delivering the recovered fluid, under high or low 
pressure conditions, along a line to a receptacle. The apparatus 
comprises, in fluid communication and in sequence, an accumulator means to 
which refrigeration fluid from the refrigeration means is drawn in gaseous 
form, a compressor to compress the refrigeration fluid from the 
accumulator and create a vacuum condition for drawing refrigeration fluid 
from the refrigerator means, and a condenser to liquify the refrigeration 
fluid for delivery to the receptacle. 
In one embodiment of the invention, particularly adapted for high pressure 
conditions (e.g. up to about 300 or 350 p.s.i.), the improvement is 
characterized by a secondary receptacle being provided, in line between 
the condenser and receptacle and communicating with the line upstream of 
the compressor, and a valve means in the line between the secondary 
receptacle and the compressor, arranged, when the vapor pressure in the 
secondary receptacle exceeds a predetermined value, so that the valve will 
open to allow some of the refrigeration fluid in the secondary receptacle 
and receptacle to flow back to the compressor for recondensation, thereby 
to lower the pressure in the receptacle. 
In an alternative embodiment of the present invention, particularly suited 
for low pressure conditions (e.g. under about 25 to 30 p.s.i.) the 
improvement comprises an elongated tubing being provided, one end of the 
tubing communicating with the line at the receptacle and the other end 
communicating with the line upstream of the accumulator, and a pressure 
regulator associated with said tubing and arranged, when the pressure in 
the receptacle exceeds a predetermined value, so that the pressure 
regulator will cause some of the refrigeration fluid to flow through the 
tubing back to the line upstream of the accumulator thereby to reduce the 
pressure in the receptacle. 
In both embodiments of the present invention described above, venting of 
refrigerant to the atmosphere when pressure conditions at the receptacle 
become critical is avoided. The apparatus of the present invention is 
simple to construct and fast and efficient in operation. For example, the 
need to cool the receptacle with water or ice is avoided since the 
apparatus according to the present invention enables the pressure in the 
receptacle to be quickly reduced, with a consequent reduction in 
temperature. 
In essence, in both embodiments, applicants solution is similar: relief of 
the vapor pressure from the top of the receptacle, by removal of 
refrigerant fluid in gaseous form from the receptacle, but containment of 
the refrigerant fluid and recycling thereof through the apparatus. This 
allows liquid in the receptacle drum or cylinder, to "boil" and cools down 
the drum or cylinder, allowing more refrigerant liquid then to enter. 
Thus, it is an object of the present invention to provide a refrigeration 
fluid recovery apparatus which is effective in controlling the vapor 
pressure in the receptacle and preventing that vapor pressure from 
becoming too high. It is a further object of the present invention to 
provide such an apparatus which will quickly and effectively relieve the 
vapor pressure from the cylinder but contain and recycle refrigeration 
fluid from the receptacle as the vapor pressure is being relieved. It is 
yet a further object of the present invention to provide such an apparatus 
which may be readily incorporated into a single unit, for ease of 
transportation and use.

DETAILED DESCRIPTION OF THE INVENTION 
In the drawings, similar features have been given similar reference 
numerals. 
Turning to FIG. 1 there is illustrated a schematic flow chart of apparatus 
in accordance with the present invention, for recovering compressible 
refrigeration fluid from a refrigerator system 2 and delivering the 
recovered fluid along the lines, as illustrated, to a receptacle in the 
form of refrigerant cylinder 4. The apparatus as illustrated comprises 
essentially an accumulator 6, to which refrigeration fluid from 
refrigeration system 2 is delivered in gaseous form, a compressor 8 to 
compress refrigeration fluid from the accumulator 6, creating a vacuum 
condition for drawing refrigeration fluid from system 2, and an air cooled 
condenser 10 to liquify the refrigeration fluid for delivery to cylinder 
4. It should be noted that line 12, from compressor 8, is passed through 
accumulator 6 where it acts as heat exchanger to boil refrigeration fluid 
which may still be in liquid form when it arrives at accumulator 6 from 
refrigeration system 2. Appropriate lines 12 extend, as illustrated, 
between these components of the apparatus, to permit flow of fluid as 
required. Preferably a filter/dryer 14 is located at the upstream end of 
the apparatus, on line 12, and an oil separator 16 is provided in the line 
between compressor 8 and condenser 10 to facilitate in purifying 
refrigeration fluid as it passes through the apparatus to refrigerant 
cylinder 4. Downstream of filter/dryer 14, before accumulator 6, is an 
inlet valve 15. The apparatus also incorporates a pressure valve 18, low 
pressure control 20, low pressure gauge 21 and high pressure control 22 
associated with compressor 8. A liquid analyzer 24, check valve 26 and 
outlet valve 28 are provided in line 12 between condenser 10 and the end 
of line 12, where it connects to refrigerant cylinder 4. High pressure 
gauge 30, as illustrated, monitors the pressure in this portion of line 
12. 
In accordance with applicant's invention, this embodiment of apparatus 
incorporates an on-board, secondary receptacle in the form of on-board 
receiver 32. The volume of on-board receiver 32 is relatively small when 
compared to that of refrigerant cylinder 4. Thus, for example, a five (5) 
pound secondary receiver 32 may be suitably used, whereas receiver 4 may 
be for instance a thirty (30) pound or fifty (50) pound receiver. The 
ratio of the volume of the receiver 32 to that of receiver 4 is preferably 
in the range of about 1:5 to 1:20. Positioned in the line between 
condenser 10 and refrigerant cylinder 4, this on-board receiver also 
communicates, through line 34, with line 12 upstream from accumulator 6, 
as illustrated. In addition, relief valve 36 is provided in line 34, as 
illustrated, as well as safety valve 38 and recycle valve 40 (the latter 
for an optional line 42 communicating with line 12 upstream from 
filter/dryer 14). 
Also forming part of the illustrated embodiment of apparatus according to 
the present invention is a three-way by-pass valve 44, and by-pass line 
46, which communicates with line 34, downstream of relief valve 36. 
In operation, during normal operation, the refrigeration fluid is liquified 
in condenser 10, and passes through liquid analyzer 24, check valve 26, 
on-board receiver 32, outlet valve 28 and three-way by-pass valve 44, to 
end up in the receiving cylinder 4. 
When pressure in cylinder 4 however increases to a predetermined value, 
relief valve 36 in line 34 opens to allow some of the refrigerant fluid, 
in the gas state, back into the apparatus, upstream of accumulator 6, to 
be recondensed. This however may not entirely solve the problem. Since the 
pressure in cylinder 4 can increase faster than relief valve 36 can 
relieve it, it may be necessary to additionally turn off inlet valve 15 
(optional) and turn off outlet valve 28. Three-way by-pass valve 44 is 
then turned so as to cut off refrigerator fluid flow at valve 28 and allow 
high pressure refrigerant vapor from receiving cylinder 4 to exit and 
travel rapidly, through line 46, to the line 12 at the beginning of the 
apparatus, where the fluid is at a considerably lower pressure, for 
recycling through the apparatus. Refrigeration fluid gas, returned to the 
upstream end of line 12, then becomes recondensed and accumulates as a 
liquid in secondary receiver 32. The receiving cylinder 4 is thus 
permitted to cool down and the recovery operation continues without delay. 
The liquid refrigerant accumulated in secondary receiver 32 is then dumped 
into the receiving cylinder 4. The receiving cylinder 4 can then be filled 
to its appropriate level (80%). 
The apparatus according to this embodiment is a medium/high pressure 
apparatus, e.g. it handles R12 (trade-mark) refrigerant which "boils" at 
about -20.degree. F. or R22 (trade-mark) refrigrant which boils at about 
-40.degree. F. The apparatus operates from about 20 inches vacuum to about 
300 p.s.i. 
Turning to the alternative embodiment illustrated in the schematic flow 
chart of FIG. 2, this is a low pressure apparatus, e.g. it handles R11 
(trade-mark) refrigerant which boils at about 75.degree. F. The apparatus 
operates from about 28 inches vacuum to about 25 p.s.i. Instead of 
receiver 4 being a cylinder, it is conventionally a drum which withstands 
only very low pressures. When operating conventional recovery apparatus, 
the vapor pressure in the drum increases to an unacceptable level. 
It will be noted that most of the main components of the apparatus of FIG. 
2 correspond to those of the apparatus of FIG. 1. In addition to air 
cooled condenser 10 there is a water-cooled condenser 50. In this case, 
however, in order to relieve vapor pressure from the top of the drum 
forming receiver 4, and to contain and recycle refrigerant in the gas 
state from the drum through the apparatus, there is a return line 52 from 
receptacle 4 to deliver refrigerant fluid (gas) upstream of accumulator 6. 
As well, incorporated in line 52 is a pressure regulator 54 and a return 
valve 56. When return valve 56 is opened, and the pressure in receptacle 4 
exceeds a predetermined value established at pressure regulator 54, that 
pressure regulator acts as an automatic valve to permit refrigerant gas to 
flow through line 52 back to accumulator 6. A further by-pass valve 58, in 
parallel with pressure regulator 54, between line 52 and line 12 as 
indicated, is provided to by-pass regulator 54 when the recovery of 
refrigerant gas is complete. This relieves the balance of excess pressure 
in receiver 4, and that receiver is then ready to be transported. 
Of note, the apparatus illustrated in FIG. 2 additionally incorporates a 
high pressure gauge 60, associated with high pressure control 22 and line 
12 upstream of compressor 8, as illustrated, liquid refrigerant flow sight 
glass 62, discharge valve 64 and conventional on-off valves 66 and 68. 
Because of the differences between the high and low pressure situations, as 
described previously, the apparatus according to the present invention 
differs somewhat in detail, from one situation to the other. The problem 
being solved however is the same: 
e.g. a high pressure cylinder may contain only one inlet port. Therefore a 
three-way valve 44 is used. 
in the low pressure apparatus, all of the excess pressure from drum 
receiver 4 can be relieved, at the conclusion of the recovery operation, 
simply by using by-pass valve 58, so that the drum can be shipped without 
pressure; 
in the high pressure apparatus of FIG. 1, an on-board secondary receiver 32 
is used to accomplish greatly improved cooling at cylinder 4, when liquid 
refrigerant is accumulated in secondary receiver 32 and not returned 
directly to the receiving cylinder. 
Thus it is apparent that there has been provided in accordance with the 
invention that fully satisfies the objects, aims and advantages set forth 
above. While the invention has been described in conjunction with a 
specific embodiments thereof, it is evident that many alternatives, 
modifications and variations will be apparent to those skilled in the art 
in light of the foregoing description. Accordingly, it is intended to 
embrace all such alternatives, modifications and variations as fall within 
the spirit and broad scope of the invention.