Liquid delivery system

A system is provided for delivering any of two or more liquids from their respective storage tanks into a tank truck or the like while avoiding contamination of the liquid being delivered with any significant amount of a previously delivered liquid. Means are provided for collecting vapor from the tank truck and for minimizing evaporation losses of the liquid being delivered.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
Many industrial operations involve the transfer of bulk liquids from 
storage tanks into tank trucks, tank cars, or other storage vehicles. 
Usually, such transfers are made through a liquid delivery system that is 
common to two or more storage tanks holding different liquids. The present 
invention is directed to such a delivery system, and is particularly 
concerned with providing means for transferring any of several liquids 
without contaminating the liquid being transferred with any significant 
amount of a previously delivered liquid. It is also concerned with 
providing means for minimizing evaporative losses and for recovering 
vapors during such transfer. 
2. Description of the Prior Art 
In industries that sell an assortment of bulk liquid chemicals, transfer of 
such chemicals from storage tanks into tank trucks, railroad tank cars, or 
other storage vehicles is frequently necessary. In most cases, such 
transfers are made through a single liquid delivery or dispensing system. 
Strangely, however, such systems seldom have means integrated therewith 
for measuring the amount of liquid transferred therethrough; instead, the 
amount of liquid so transferred is determined by weighing the storage 
vehicle before and after the filling of its storage tank, or by filling 
said storage tank up to a predetermined liquid level. 
The primary reason that the amount of transferred liquid is measured by 
such methods is that the most widely employed liquid metering means, the 
positive displacement, nutating-piston meter, if employed in such a liquid 
delivery system, would, during the subsequent draining of said system, 
entrap a significant amount of liquid in both the nutating meter itself 
and its associated piping. The total amount of liquid so entrapped may 
range between about 3 and 5 gallons, assuming the meter is of commercial 
size. Hence, a liquid delivery system incorporating such a meter could not 
be effectively utilized to transfer any of a plurality of liquids because, 
after a first liquid is transferred, none of the others could be 
transferred through the same system without being contaminated with a 
significant amount of said first liquid. 
Another problem inherent in using commercially available liquid delivery 
systems resides in the vapor removal means usually employed therewith to 
remove vapors emitted from the liquids entering the vehicle storage tank. 
The presently accepted means for removing such vapors entail means for (a) 
sealing the gases within the storage tank from the surrounding atmosphere 
and (b) drawing said gases out of the storage tank during the filling 
thereof with liquid. While such means are effective for removing the 
vapors, they also totally obstruct a workman's view into the vehicle 
storage tank, thereby increasing the likelihood of flooding the vapor 
removal means with liquid or filling the entire vehicle storage tank with 
the wrong liquid. Moreover, environmental protection agencies in some 
states, including the State of California, require that vapor withdrawal 
from vehicle storage tanks in the manner described (i.e., by sealing the 
vapors from the surrounding atmosphere) be accomplished at a pressure 
substantially less than atmospheric, thus resulting in the volatilization 
and loss of more of the liquid entering the storage tank than would occur 
if the vapor removal were accomplished at essentially atmospheric 
pressure. 
It is accordingly an object of this invention to provide a liquid delivery 
system capable of transferring an accurately measured amount of a liquid 
from one vessel to another while avoiding contamination of said liquid 
with any significant amount of a liquid previously transferred through the 
same system. Another object is to provide, in such a delivery system, 
means for collecting vapors evolved from the receiving vessels while 
permitting visual observation of the operation. A further object is to 
provide, in such a system, means for minimizing the amount of liquid 
vaporized during delivery. Other objects and attendant advantages will be 
apparent from the following detailed description of the invention. 
SUMMARY OF THE INVENTION 
The apparatus of this invention comprises a liquid delivery system to be 
utilized for transferring accurately measured amounts of any of a 
plurality of separately stored liquids into receiving vessels without the 
transferred liquid being contaminated in said system with a significant 
amount of a previously transferred liquid. The transfer of an essentially 
uncontaminated, accurately measured amount of a liquid is insured by 
incorporating a turbine meter of high accuracy in a liquid delivery system 
comprising a pump and a liquid loading arm. Such meters are essentially 
completely drainable through a fluid communication path including their 
intake and discharge openings; hence, when the entire liquid delivery 
system must be drained after the passage of a liquid therethrough, no 
liquid will be "held-up" either in the meter or its associated piping. 
The delivery of an accurately measured amount of a liquid is insured not 
only by the use of a turbine meter of high accuracy but also by the use of 
means for removing entrained gases from a liquid prior to its passage 
through said meter. Additionally, a control valve is used in conjunction 
with said turbine meter to insure that only an entrained gas-free liquid 
passing through said valve is measured by said turbine meter and delivered 
to the receiving tank. 
Vapor removal means, comprising a vapor collection head situated on said 
loading arm, a fan, and suitable conduits for transporting gases from said 
vapor collection head to said fan and from thence to suitable vapor 
disposal facilities, are included in the apparatus of the invention. The 
vapor collection head, however, when placed in position on the rim of the 
receiving tank hatchway, is designed not to effect a vapor-tight seal 
between the gases in said receiving tank and the surrounding air, thereby 
providing for viewing into the tank and for removing vapors therefrom at 
essentially atmospheric pressure.

DETAILED DESCRIPTION OF THE INVENTION 
As shown in FIG. 1, the apparatus of the invention comprises gas eliminator 
tank 19 which is connected via line 18 to a plurality of liquid storage 
tanks. Liquid is transferred from the storage tanks to a receiving tank 3 
via gas eliminator tank 19, tee 21, elbow 22, line 24, turbine meter 16, 
line 25, control valve 34, line 11, and loading arm 10. Vapors are removed 
from receiving tank 3 into line 51 via vapor collection head 9, which 
engages only an arcuate portion of rim 12 of hatchway 13, thereby 
providing atmospheric communication with the interior of said tank. 
To describe the invention with more particularly, FIG. 1 shows two 
underground storage tanks 1 and 2, liquid A being stored in tank 1 and 
liquid B in tank 2. To pump a measured quantity of liquid A into tank 3 of 
tank truck 4 valve 59 is open, valve 58 is closed, and three-way valve 5 
is set to deliver liquid through lines 6 and 7 and to block any flow of 
liquid through line 8. 
When vapor collection head 9 engages the rim 12 of the hatchway 13 leading 
into tank 3, switch lever 14 rotates about pintle 57 and contacts 
electrical terminal 15. When gallonage counter 60 in turbine meter 16 is 
set to record the passage of a specified number of gallons of liquid, 
which setting closes switch 44 located within said turbine meter 16, the 
electrical circuit shown in FIG. 2 is completed and positive displacement 
pump 17 is activated. Liquid A is then pumped upwardly through line 7 and 
forced into pipe 18 leading into gas eliminator tank 19 containing, as 
shown in a partial cutaway view, a baffle 41 with drain holes 42. As the 
liquid rises in tank 19, it also passes into drain return line 20, tee 21, 
elbow 22, vent line 23, lines 24 and 25, and turbine meter 16. Eventually 
it forces float 26 to rise. When the liquid reaches a level such that 
float arm 27, which is pivotably mounted in pipe 28 to two suitable 
carriages (one shown as reference numeral 30) by means of two trunnions 
(one shown as reference numeral 29), assumes a substantially horizontal 
position, valve head 31, drawn by stem 32, seats against the top of 
annular valve seat 33. 
Once valve head 31 is seated as described, liquid is forced to continue 
rising only in vent line 23 and line 25. With control valve 34 being in 
the closed position, the liquid rising in line 25 will force air and other 
gases into air vent tube 35, which is situated to pass such gases from the 
high point of line 25 into vapor removal line 39 via conventional air vent 
float valve 38. (A suitable float valve for purposes herein is a 
Brooks-Brodie Model No. W 180215). Meanwhile, rising liquid in vent line 
23 also forces air into line 39, firstly by displacing air in vent line 23 
itself, and secondly by displacing air in float switch arm 36 through 
conventional float switch 40, air bleed line 37, and float valve 38. When 
the liquid level in vent line 23, line 25, and arm 36 reaches a height 
such that liquid is just beginning to enter air vent tube 35 from line 25, 
air vent float valve 38 closes, thereby shutting off the flow of gases 
into line 39. Simultaneously, float switch 40 closes, thereby completing a 
second electrical circuit shown in FIG. 2, which completed circuit 
energizes solenoid 61 within control valve 34 so that said valve opens to 
allow the flow of liquid into line 11. 
Liquid now passes into tank 3 of tank truck 4 through line 11 and loading 
arm 10, the latter being comprised of loading arm conduit 55, elbow 56, 
and sliding pipe 47. It is preferable that the tank be filled from the 
bottom so that vaporization of liquid due to aeration effects is 
minimized; consequently, sliding pipe 47 is pushed through vapor 
collection head 9 until stop ring 48 contacts the floor of tank 3, thereby 
introducing liquid into the bottom of said tank through discharge holes 
49. 
The amount of liquid pumped into tank 3 is volumetrically measured by 
turbine meter 16 and recorded on gallonage counter 60. Preferably, a 
turbine meter is used that is at least accurate to within .+-. 0.05 vol. % 
of the amount of liquid delivered; such meters may be obtained 
commercially. As those skilled in the art will realize, turbine meters 
depend for their accuracy upon a "straightened" flow of liquid passing 
therethrough. Hence, lines 24 and 25 are of sufficient lengths C and D, 
respectively, to provide the necessary straightening effect for turbine 
meter 16. Additionally, line 24 may contain internal straightening vanes 
to aid in this purpose. 
When the predetermined number of gallons has been pumped through control 
valve 34 and been recorded by the gallonage counter 60, an appropriate 
trip mechanism, such as a relay, not shown, in turbine meter 16, will trip 
switch 44, thereby shutting down positive displacement pump 17 and 
de-energizing solenoid 61 so that control valve 34 closes. To insure that 
the required quantity of liquid passes through control valve 34, it is 
preferred that the specified number of gallons initially set on gallonage 
counter 60 includes the constant number of gallons that pass through 
turbine meter 16 prior to the opening of control valve 34. For example, if 
1500 gallons are desired to be delivered and 5 gallons will pass through 
turbine meter 16 prior to the opening of control valve 34 as previously 
described, then it is necessary to set gallonage counter 60 to record the 
passing of 1505 gallons to insure that the proper amount is delivered. 
Alternatively, gallonage counter 60 can be so adjusted that it "zeroes" 
when 5 gallons has passed therethrough. In such an embodiment, it is only 
necessary to set gallonage counter 60 at 1500 gallons to insure that the 
desired quantity of liquid passes through the control valve 34. 
When control valve 34 closes in response to the tripping of switch 44, a 
portion of the specified delivery of liquid will be held within line 11 
and loading arm 10. To drain this entrapped liquid into tank 3, control 
valve 34 is equipped with a conventional diaphragm actuated, vacuum 
breaker valve 45, which opens to the atmosphere when the negative pressure 
exerted on said valve 45 by the entrapped liquid is detected. The force of 
gravity then drains the remaining portion of the specified delivery as 
indicated on gallonage counter 60 into tank 3. 
The accuracy with which the amount of liquid transferred into tank 3 is 
measured herein depends not only upon utilizing a turbine meter of high 
accuracy but also upon insuring that the liquid passing through turbine 
meter 16 contains no entrained gases, which may otherwise introduce 
significant errors in the reading shown on the gallonage counter 60. 
Accordingly, means are incorporated herein for preventing the passage 
through turbine meter 16 of any significant volume of entrained gases. Any 
entrained air or other gases entering tank 19 during the delivery of a 
liquid (e.g., by the introduction of air through the seals of pump 17) are 
collected in the upper portion of tank 19, and when a sufficient amount 
collects therein so as to lower float 26, they are automatically 
discharged via line 46. Moreover, in the rare event any entrained gases do 
enter tee 21, most of such gases will bubble up line 23, thereby tripping 
float switch 40 and closing control valve 34, the latter of which re-opens 
only when rising liquid once again forces essentially all the gases that 
entered tee 21 out line 39. Thus, by eliminating gases from the liquid 
prior to its passing through turbine meter 16, and by providing for 
immediate shutdown in the event that some gases do enter tee 21, the 
reading shown on gallonage counter 60 always reflects the true amount of 
liquid passed through control valve 34; hence, extremely accurately 
measured deliveries of a liquid transferred into tank 3 are obtained. (One 
embodiment of the invention as described was found to be accurate within 
.+-. 1 pint per 500 gallons pumped at a rate of about 150 gpm. For 
purposes herein, however, an accurately measured delivery is obtained when 
the amount of a liquid delivered into a receiving vessel at a rate between 
about 10 and 200 gpm is within about .+-. 0.1 vol. % of the amount 
indicated by the turbine meter or other liquid metering means hereinafter 
defined.) 
An essential feature of the invention is its drainability, which allows the 
transfer of the second liquid, liquid B, through the same liquid delivery 
system as was used to transfer liquid A without therein contaminating 
liquid B with any significant amount of the previously transferred liquid 
A. As shown hereinbefore, liquid A entrapped downstream of control valve 
34 is removed by the automatic opening of vacuum breaker valve 45. The 
remainder of the liquid delivery system is drained through valve 59 by 
operating (by means of an electrical circuit not shown) positive 
displacement pump 17 in reverse. Since positive displacement pumps can be 
used to pump and compress air, essentially all the remaining liquid 
entrapped in the delivery system may be pumped back through valve 59, 
which is then closed. Alternatively, the force of gravity alone may be 
utilized to drain this remaining liquid entrapped in the liquid delivery 
system if pump 17 is capable of being drained in a reverse direction, and 
if no component of said system between valve 59 and control valve 34 is 
designed to retain a liquid draining freely by the force of gravity. 
However, reverse draining through the pump in this manner alone may be too 
slow; hence, bypass line 50 is provided to increase the flow of liquid 
into the respective storage tanks. 
The essentially complete draining of the liquid delivery system by the 
methods herein described is dependent upon the use of a turbine meter 16, 
or other liquid metering means having its intake and discharge openings 
terminating the ends of a fluid communication path passing through said 
metering means, through which openings and fluid communication path a 
liquid may pass without any significant amount thereof being entrapped 
therein or in any components associated with said liquid metering means. 
In essence, then, only those meters that will drain essentially completely 
through a fluid communication path passing through their intake and 
discharge openings, and that will permit essentially no "hold-up" of 
liquid either in themselves or in other parts of the liquid delivery 
system during the draining thereof, are contemplated for use in the 
invention. Specifically excluded as a component of the invention, 
therefore, is the most commonly used liquid metering means, the typical 
nutating-piston meter, the use of which, as stated hereinbefore, may cause 
the entrapment of between 3 and 5 gallons of liquid. If a subsequent 1500 
gallon delivery of another liquid product were to be passed through a 
liquid delivery system comprising such a meter, the final product 
delivered would be contaminated with between about 0.20 and 0.33 volume % 
of a previously delivered liquid. Contaminations of this magnitude may be 
intolerable and are avoided when a turbine meter is utilized as a 
component of the apparatus of the invention. 
After the liquid delivery system has been drained of liquid A as described, 
liquid B may then be safely transferred therethrough into a recovery tank 
without being contaminated with any significant amount of previously 
delivered liquid A. Preferably, the draining of the liquid delivery system 
has been so complete that, when liquid B is transferred therethrough, it 
will be contaminated with no more than that residual amount of previously 
delivered liquid A that clings to the interior walls of the liquid 
delivery system and is removable therefrom, if at all, only by 
evaporation. The amount of this evaporative residual of liquid A that will 
be present in said liquid delivery system immediately subsequent to the 
draining thereof will depend firstly upon the internal surface area of the 
delivery system, which for purposes herein should be at least 25 ft.sup.2, 
preferably between about 100 and 300 ft.sup.2. It will also depend upon 
the nature of the delivered liquid. For liquids boiling above about 
200.degree. F., usually no more than 50 cc will remain as an evaporative 
residual in a liquid delivery system having an internal surface area in 
the preferred range; however, if the liquid is a highly volatile organic 
liquid, such as hexane, kerosene, toluene, xylene, a mineral spirit, or 
gasoline, that tends rapidly to evaporate from the interior walls when air 
is drawn through the apparatus by the draining of the liquid delivery 
system, less than about 25 cc will remain as an evaporative residual in 
said system. For purposes herein, however, a liquid is delivered 
essentially uncontaminated with, or contaminated with less than a 
significant amount of, a previously delivered liquid when it is delivered 
in a state contaminated with no more than 250 cc of said previously 
delivered liquid in excess of the evaporative residual. 
If liquid A or B is organic in nature, vapor removal may be necessary to 
satisfy local air pollution regulations. Accordingly, provision is made 
herein to prevent the escape of vapors therefrom during delivery into tank 
3. Some are removed via lines 39 and 46 when the liquid delivery system is 
being initially filled and when float 26 or the float in float switch 40 
is lowered due to the collection of gases as hereinbefore described. The 
removal of most vapors, however, is accomplished via line 51 leading to an 
air eduction means, such as a fan not shown, that draws vapors from tank 3 
through openings 52 in vapor collection head 9, from which said vapors are 
carried by line 51 and induced by said air eduction means to conventional 
vapor recovery or disposal facilities, not shown. 
It is emphasized that the vapor collection head 9 does not connect to 
hatchway rim 12 in vapor-tight fashion. Instead, it is preferred that it 
be designed so that, in use, it will sit on only a portion, preferably 
only a minor portion, of rim 12 and contact no portion of the inner 
surface of hatchway 13. Thus, the air eduction means draws a mixture of 
the vapors present inside the tank 3 and the air present outside said tank 
3 into the collection head 9. 
Two advantages reside in the use of a vapor collection head 9 of the 
preferred design. Firstly, it allows the person who is filling the tank 3 
to see thereinto so that, if the wrong liquid is pumped or if there is 
danger of overflow, he can simply raise the loading arm 10, thereby 
disengaging switch lever 14 from electrical terminal 15 so that control 
valve 34 closes and pump 17 shuts down. Secondly, since the vapors are 
being withdrawn essentially at atmospheric pressure, rather than at a 
substantial negative pressure as would be the case when tight fitting 
collection heads are utilized, less liquid is vaporized; hence, the 
customer loses less of the purchased liquid, sometimes saving up to 1 
gallon of the liquid in 500 gallons pumped, depending on the nature of the 
liquid. 
A safety feature is introduced into the invention when the loading arm is 
suspended from an appropriate platform (not shown) by means of spring 
loaded device 53 (shown in cutaway and breakaway fashions), which is both 
pivotably connected to loading arm 10 at 54 and maintained in a state of 
tension whenever vapor collection head 9 contacts rim 12. Thus, if an 
accident should befall a workman holding the loading arm 10 such that he 
should lose his grip thereon, the entire loading arm 10 will spring 
upwardly a sufficient distance such that switch lever 14 disengages 
electric terminal 15, thereby causing control valve 34 to close and cease 
the flow of liquid into the tank. This may prevent the compounding of one 
accident into a second, especially if the liquid being pumped is highly 
flammable. 
For ease in removing vapor collection head 9 from the truck tank 3, a 
second stop ring 43 is provided on sliding pipe 47. Hence, when the 
loading arm 10 is to be lifted out of tank 3, stop ring 43 will prevent 
the lower portion of sliding pipe 47 from being lifted without also 
lifting vapor collection head 9. Moreover, to accommodate all truck or 
rail car tanks into which liquid is to be delivered, stop ring 43 should 
be spaced from stop ring 48 so that for even the tank 3 of minimum depth, 
the vapor collection head 9 will sit on its rim 12 and stop ring 48 will 
contact its interior floor. 
Alternative embodiments of the invention as described are possible. The 
storage tanks may be so elevated that the liquids may be gravity fed into 
receiving vessels, in which case a pump would only be necessary for 
returning liquids to said tanks. The turbine meter may be placed 
downstream of the control valve, and in this position, liquid hold-up in 
the meter would drain into the receiving tank. The control valve may be 
hand operated with control means only being necessary to close said valve 
in the event entrained gases should enter tee 21. Also, it is possible for 
the vapor collection head to be of the vapor-tight fitting variety 
provided the receiving tank is vented to the atmosphere by means of an 
opening other than the hatchway; hence, the vapors will still be removed 
from the tank at essentially atmospheric pressure and a workman can view 
thereinto through the vent opening. Accordingly, it is intended that all 
such alternatives, and others that are apparent to those skilled in the 
art in light of the foregoing description and fall within the spirit and 
scope of the appended claims, be embraced in the invention herein.