Photography – Fluid-treating apparatus – Having fluid-circulating means
Reexamination Certificate
2000-06-15
2001-05-29
Rutledge, D. (Department: 2851)
Photography
Fluid-treating apparatus
Having fluid-circulating means
C210S304000, C210S312000, C366S144000, C366S171100, C096S210000
Reexamination Certificate
active
06238110
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the invention
The present invention relates to the field of preparing baths for the processing of photographic materials. The invention further relates to a manifold adapted for separating liquid and gas. The invention still further relates to a use of the manifold for preparing a processing bath.
The invention addresses the field of preparing or replenishing baths of liquids in applications, where there is a need to avoid gas bubbles and foam in the bath, and where there is a desire to minimize agitation of the body of liquid held in the bath. Such concerns arise in applications with liquids prone to enter undesired reactions with air, where air locks may form, and/or where agitation in the liquid may give rise to uncontrolled variations in the processing conditions. These considerations may have particular importance in connection with liquids containing surfactants that enhance their propensity to form foam and bubbles.
One field of application, where these considerations apply, is the field of baths for photographic processing.
The processing solutions or development liquids used are in many cases highly reactive and very likely to react with substances in the air, e.g. with oxygen. The development liquids may also comprise tensides or other surfactants including them to foam formation. The surfactants are important for furthering desirable properties of the processing solutions, e.g. for making the liquids effective towards dissolving and stripping off non-exposed areas of emulsion within a photographic piece of material.
However, surfactants make processing solutions susceptible to foam formation on pumping and agitation, as may occur during replenishment of the tank. The foam may clog vents and pipes and may cause spill over. Problems with excessive foam formation may lead to the decision to avoid the surfactants, thus forgoing their desirable capabilities in other aspects.
2. Description of the Prior Art
U.S. Pat. No. 5,309,191 describes an apparatus adapted for replenishment and flushing of a tank which forms part of a photographic processing apparatus. The apparatus comprises replenishment tanks, a manifold, a pump, and valves for permitting controlled introduction of processing solution into a tank. The inlet for the processing solution is at the bottom of the tank with the view to avoid air from being entrapped in the processing apparatus.
Feeding in liquid at the bottom of the tank requires the establishment of a fluid conduit, which is inherently open to undesirable backflow into the feed piping, e.g. during time intervals when the feed pump is stopped. The risk of backflow may be encountered, e.g. by the installation of active means, such as check valves.
However, for considerations of safety and reliability it would be preferred to have a system where the prevention of backflow would not need to rely on the performance of active means.
Feeding in liquids through a manifold placed below the liquid surface level makes it complicated to maintain complete separation between different ingredients intended to be mixed in the bath. This is a concern since the ingredients, when in a concentrated state, may be susceptible to enter undesirable reactions among them, e.g. to form gel. Feeding in liquid at the lower portion of the tank does not completely avoid the risk of introducing air bubbles since the feed pipe may occasionally suck in air, e.g. during a phase when the replenishment tank is being emptied.
U.S. Pat. No. 5,622,545 discloses a separator for removing gases from water for the purpose of treating water for fish aqua cultures. The separator comprises a vortex tube wherein water is injected to spin downwardly while gas may exit the separator through a gas exit port at the top.
U.S. Pat. No. 3,044,236 discloses a system for removal of gases from liquids in order to prepare gas-free samples from chemical process streams prior to their analyses. The system comprises a gas disengager, wherein a gas-liquid mixture is introduced tangentially with the purpose of stripping away any gas. A weir serves to limit variations in hydrostatic head.
SUMMARY OF THE INVENTION
The invention in a first aspect provides an apparatus for the preparation of a bath for processing photographic material, comprising a tank adapted for holding the bath, a container for holding a feedstock fluid and a separator in fluid communication with said container by first fluid conduit means and in fluid communication with said tank by second fluid conduit means, said separator comprising a fluid inlet port communicated with said first fluid conduit means, a liquid outlet communicated with said second fluid conduit, a vent opening, means for skimming excess foam away from said separator and flow diversion means adapted for engaging a stream of feedstock fluid introduced through said inlet port and for guiding the stream along a curved path in order to separate the fluid into gas and liquid by a cyclone action and for conveying the liquid through a laminar flow regimen into a collection region, communicated to said liquid outlet.
This apparatus receives a feedstock fluid from a container, strips away any gas from the fluid, and guides the liquid to a collection region, from which the liquid discharges in such way that it may be introduced into the bath with a minimal agitation. The gas escapes the separator through the vent opening. The liquid introduced into the bath holds a minimal content of gas, and it is introduced with minimal pouring of the bath. The separation of gas from the liquid is achieved by a cyclone action. The cyclone action enhances separation of gas and liquid according to their differential specific gravities.
The separator effectively performs a three-way separation function; discharging gas through the vent opening, foam through the drain, and liquid through the liquid outlet. This apparatus is effective in the handling of highly surface-active fluids.
Preferably, the cyclone action involves the forming of a laminar flow regimen in a thin layer of fluid in contact with a peripheral wall surface. The thin layer of fluid shortens the distance any air bubbles need to cover in order to escape the liquid. The laminar flow involves a flow regimen where the velocity is lower near the wall surface and higher away from the wall surface, i.e. towards the axis of the cyclone. The differential velocities give rise to a dynamic pressure gradient, which furthers separation of gas and liquid. The collection region allows the liquid to settle, while permitting any gas bubbles to escape.
The vortex motion may be imparted by active means, e.g. by propellers, blades or rotating chambers active to impart a body of fluid a rotating motion. However, according to a preferred embodiment, the vortex motion is achieved by guiding the stream of fluid entering the separator through the inlet port and along a tangential direction towards the inside of a curved wall, thus utilizing the momentum of the stream of fluid so as to create a vortex motion.
According to a preferred embodiment, a weir, preferably associated with a drain, communicated to a receptacle, controls the level of liquid in the separator. The weir is effective to cap excess build-up of foam inside the separator so as to avoid any possibility of foam rising to clog the vent opening. On the other hand, the weir may be situated at a level above the inlet ports, as the foam has been found to cause no problems with the inlets. Any foam held in the separator below the level of the weir and above the surface of liquid is allowed to settle down.
According to a preferred embodiment, the apparatus is associated with means for keeping the level of liquid below a maximum level, which is below the level of the inlet port. This avoids any risk of liquid flowing backwards through the inlet port. The means for controlling the level of liquid may comprise passive means, such as an overflow or a weir, or they may comprise active means, such as a level sensor associated with means for controlling the rate of intake and/or
Jensen Tommy
Thorup Jens Havn
Wegge Henrik
Glunz & Jensen A/S
Rutledge D.
Vigil Thomas R.
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