Vessel Specialties, Pad-Depad Blanketing. The term PAD (tank blanketing) is the process of replacing the vapor of a storage tank with an inert gas. The term DEPAD (vapor recovery) is the process of relieving or venting the vapor space in the event of a pressure rise. A pad-depad valve is a self-contained, pilot-operated valve that maintains a blanket of inert gas on top of a stored product to protect it from atmospheric contamination. This reduces combustibility, decreases vaporization, controls vapor space pressure during in and out pumping operations, and helps to prevent the tank from entering a vacuum condition causing it to collapse.
Things to Consider: Pad: Body size, Temperature capabilities for materials of construction, Maximum operating inlet pressure, Maximum main valve inlet pressure, Minimum main valve inlet pressure, Pressure registration; Depad: Body sizes, Temperature capabilities for materials of construction; Weights; Accessories: Gauges, purge meters, pressure switches, and check valves.
Vessel Specialties, Coatings & Linings. Pressure vessels coatings and linings are applied for two reasons: to protect the vessel from the chemicals being processed, or to protect the material being processed from contamination by the vessel. The type of coating required depends upon the application. The following is a sampling of the available types: thermoplastic sheet-lining, elastomeric sheet lining, masonry linings, borosilicate glass, and organic and metallic coatings.
Things to Consider: Color, Finish, Hydrophobic or hydrophilic, Film thickness, Adhesion, Heat resistance, Pigments, Solids content, Abrasive resistance (Taber wheel), Surface Hardness (Konig pendulum DIN 531157), Thermal shock (unaffected in specified number of cycles for specified temperature range), Flexibility (Zuhr conical mandrel), EPA and USDA requirements.
Vessel Specialties: Sightglass/Tank Light. A sightglass is a small window providing visual access to the inside of a process vessel. They are fabricated using durable glass that is securely fixed into a metal mounting frame. Tank lights, usually LED devices, are long-life lighting devices that illuminate the inside of a process vessel for inspection. Some units are available with integrated windows, eliminating the need for a separate sightglass at the installation site.
Things to Consider: Agency approvals, Certification for material and pressure rating (ASME), light intensity, NEMA 4, IP66; Explosion proof, Class I, Div. 1 Group B, C & D, Class II, Div. 1, Groups E, F & G; Flameproof EEx d IIC T6 Ratings, One piece sanitary construction, Connection type, Cool light output to prevent product bake on, ASME BPE / FDA / USP compliant, Ease of removal for cleaning; Fiber optic bundle construction, exterior, termination and lengths.
Vessel Specialties, Spray Balls. Spray balls are attached to output pipes of a machine’s CIP (Clean in Place) fluid delivery system. They are hollow spheres with holes that create a spray when pressurized with cleaning or sanitizing solution. Spray balls are of two types; stationary and rotating . Where stationary type spray balls do not provide sufficient impact in cleaning, rotating or spinning spray balls can be used. Spray balls defined by their cleaning radius, which varies from 1 to 10 feet, depending upon the capability of the cleaning fluid pressure pump, which must deliver enough volume and pressure to the spray ball to ensure that it can deliver enough pressure to the surface being cleaned.
Things to Consider: Recommended flow, Tank diameter at specified pressure, Head depth to side wall, Maximum achievable flow rate versus ball diameter, Supply connection size, Tank port connection size, Insertion depth, Solution tube OD, Pin hole location, Drill diameter.
Tank Breathers. These are components, normally installed into a threaded port that breaches the tank wall, that allow air to pass in and out of the tank to compensate for changes in the tank’s internal pressure. Breathers are usually filtered and partly self cleaning. When air enters through the breather, contaminant particles are trapped at the surface of the breather’s filter. When air is expelled through the breather, it forces the contaminants back into the environment. When the air is expelled from the container, the pleated filter cleans itself by releasing dirt back into the atmosphere. When breathers are no longer performing efficiently, they can be easily replaced.
Things to Consider: Filtration efficiency, Capacity (CFM), Air flow pressure drop (PSI at specified air flow), Prefilter option, Dirt holding capacity, Weatherhood, Entrance velocity, Finish, Tubular silencer option, Connection type, Materials of construction, Colored for visibility.