The Proper Guide to Tank Cleaning

The Proper Guide to Tank Cleaning

Proper tank cleaning is paramount to ensuring the highest possible quality of your product. However, in the busy atmosphere of managing a company, this task can be forgotten, neglected, or simply ignored – a potentially dangerous oversight. Neglecting to clean your tanks properly can mean leftover residue from previous batches is left. For example, beerstone can build up and shorten the shelf life of beer – or even ruin the entire batch. The list could go on. Simply put, properly cleaning tanks is essential to any industry utilizing such equipment. The content below explores each facet of tank cleaning in depth. We begin by discussing the fundamentals of tank cleaning technology and specific cleaning efficiency classes. Then, we explore specific planning criteria, nozzle types and their operating principles, connection options, and our unique TankClean simulation software. The goal: to provide a helpful guide to plan a perfect tank cleaning process.

The Fundamentals of Tank Cleaning Technology

Four Main Cleaning Factors

Chemistry, time, temperature, and mechanical action are the four basic principles of tank cleaning. Each principle plays a vital role in an efficient cleaning process. Utilizing the right equipment achieves a perfect balance between each factor. This balance accomplishes the most efficient tank cleaning process possible with efficiency, precision, and reliability as the end goals.

1. Chemistry

  • Safety first. Regardless of what cleaning agent is employed, properly handling and distributing the solvent is crucial to a safe cleaning process.
  • Less is more. Using too much chemical agent could deteriorate your tank; too little may clean improperly, leaving grime or dirt behind.
  • Choose the correct chemical. Utilizing the correct chemical for your application is important. Finding that correct chemical is less obvious. The types of tank cleaning chemicals can be organized in three categories: highly alkaline detergents, highly acidic cleaners, disinfectants. Alkaline detergents eliminate proteinaceous, organic soils. Acidic cleaners are suited for the removal of inorganic soils, such as beerstone or water stains. Disinfectants kill microorganisms, such as bacteria.

Alkalis and acids work concurrently to clean and disinfect tanks. For example, alkalis are utilized to eliminate grease, grime, dirt, organic soils, etc. Any remaining inorganic buildup must be removed with an acidic detergent. In an excellent study about brewing techniques, Greg Foss describes the different roles of alkalis and acids in a helpful illustration. Home-washed dishes are cleaned with an alkalis detergent, excellent for removing everyday dirt and grease. Over time, however, stains can form on the dishes that require more than a simple detergent. Soaking the dish in a household acid, such as vinegar, dissolves the stain.

2. Time

Time can be a challenging variable. The time it will take to clean your tank properly depends on fluctuating factors, such as your tank type, soil type, and level of soil concentration. Utilizing a CIP system can help keep preparation and time results consistent.

3. Temperature

The proper chemicals must be used at the right temperature to avoid adverse chemical reactions or disruptions. Chemical providers will offer recommended temperatures as well as automated cleaning mechanisms. Pay attention and consistently employ the exact temperature recommendations for your chemical for optimal use.

4. Mechanical

A reliable mechanical nozzle system will reduce water consumption and chemical costs. As seen in the adjusted pie chart, the right nozzle for your application will cut temperature, time, and chemistry costs. For example, rotational spray nozzles can reduce solvent consumption by 30% and shorten the cleaning cycle by 40%.

How can one choose the best nozzle for their specific application? When planning, begin by considering impact, flow rate, and pressure.

Impact: Impact refers to the rate at which a droplet strikes the tank wall. The specific area where the droplet hits is an impact surface. Nozzles are categorized as high or low impact. For example, solid stream nozzles or flat fan nozzles are high impact, striking the impact surface at high intensity.

Flow Rate: Flow rate and impact are correlated. To illustrate, increased flow rate increases impact, presuming other parameters – such as spray angle, pressure, and medium – remain static.

Pressure: Rotating cleaning nozzles deliver the greatest impact when cleaning the surface area of the tank. To achieve this, large droplets must strike at high speed. Important influencing factors are the distance between the nozzle and wall, and the operating pressure. If either are too great the fluid will break down into smaller droplets and the impact will be reduced. Similar to temperature, rotating nozzle suppliers, such as Lechler, should provide a recommended operating pressure range for maximum impact efficiency.

Cleaning Efficiency Classes

For organizational purposes, tank cleaning nozzles are clustered into classes, making it simple to choose the right nozzle for a specific application. Nozzles in each class are defined by the soil type being cleaning, including light, medium, and persistent.

Cleaning Efficiency Class One: Nozzles placed in class one are designed for rinsing with a flow rate of 4.0 to 89 gpm at 20 psi. This specific flow rate is often required in the food and beverage industry. Class one nozzles can be used with liquid mediums as well as steam, air, and SIP-cleaning (Sterilization in Place). Static spray nozzles, discussed in detail momentarily, are placed into class one, designed to operate under high temperatures and guarantee high process reliability.

Cleaning Efficiency Class Two: Class two nozzles are designed for removing light soils, often those that occur in the food and beverage industry, as well as the chemical and pharmaceutical industry. Nozzles in this category are made of high-grade materials, such as stainless steel, PVDF, PEEK, and PTFE. Strong materials allow for efficient use among a wide range of cleaning agents.

Cleaning Efficiency Class Three: Class three flow rates range from 3 to 303 gpm at 30 psi, excellent for cleaning medium soiling from tanks and equipment. Class three nozzle geometry is uniquely designed for efficient cleaning in the food and beverage industry, as well as the chemical and pharmaceutical industry.

Cleaning Efficiency Class Four: Class four nozzles are excellent for heavy soiling, can withstand high temperatures, and are suitable to contact with food. Class four nozzles are implemented to clean large tanks and use controlled rotation.

Cleaning Efficiency Class Five: The peak of cleaning intensity, class five nozzles are utilized for serious cleaning projects with heavy soiling. Three primary industries utilize high impact tank cleaning nozzles: food and beverage, chemical and petrochemical, and paper. Used for medium to very large tanks, solid jet nozzles ensure total cleaning efficiency with maximum impact.

Planning Criteria

Beyond Cleaning Efficiency Classes, certain logistical criteria should be considered during the planning process.

1. Nozzle Arrangement: Nozzles must be positioned in specific places inside the tank, preferably near the upper half. This accurate positioning ensures that sufficient cleaning fluid strikes the top. We recommend the following as best practice: = 1/3 · Htank and Hnozzle  < 1/3 · Dmaxspray diameter nozzle 

Furthermore, because the nozzle should never come into contact with product, the nozzle should be positioned above the maximum product level in the tank.

2. Pump and Pipes: Determining proper pipe size depends on required flow rate. Once a required flow rate is determined, the proper pipe should be chosen to minimize pressure loses. Both pump power and the nozzle connection point must match the required static operating pressure.

3. Drain Hole Size: A tank’s drainage rate must prevent the liquid from rising during the cleaning process. The drain must be built to handle the volume of liquid implemented. The chart below provides helpful guidelines into drain hole size and volume capacity:

 

1”

6 gal/min

1 ½”

13 gal/min

2”

23 gal/min

2 ½”

35 gal/min

3”

50 gal/min

4”

87 gal/min

4. Number of Nozzles: In certain instances, multiple nozzles are required to effectively and efficiently clean the tank surface area. For example, large tanks or complex installations require several nozzles, positioned to allow spray jets to overlap.

5. Tank Obstructions: Spray shadows, improperly cleaned areas of the tank, can also form. Spray shadows often develop behind tank obstructions, such as agitators, mixing blades, baffles, and coils. Eliminating spray shadows can begin by simply removing certain internal obstructions. Of course, removing any obstructions adapts your SOP, adding removal, reinstallation, a COP system, and – ultimately – time to the process. Rotating nozzles (discussed in detail below) provide an efficient solution to spray shadows, cleaning around tank obstructions. When placed in key positions inside a tank, rotating nozzles compensate for the shadowing effect. For efficient cleaning of tank obstructions, such as agitators, Lechler provides specific nozzles, such as the compact PopUp Whirly, that are efficient in confined spaces.

Nozzle Types and Their Operating Principles

Static: Static spray balls are classified in Cleaning Efficiency Class One and primarily utilized for rinsing smaller tanks or vessels. Because the cleaning system does not rotate, cleaning gaps can occur in the spray pattern. A similar issue can occur if a rotating spray nozzle simply stops turning.

Despite these weaknesses, static spray balls provide distinct advantages, making them indispensable for certain tasks. They are self-draining, easy to inspect, and excellent for use in hygienically sensitive environments.

However, rotating nozzles deliver a unique power and efficiency to the tank cleaning process that is simply unachievable via static spray ball use. The following three nozzle types are classified as “rotating nozzles.”

Free-spinning: Free-spinning nozzles are fluid-driven. Placed in Class Two and Three, these nozzles are excellent for light soiling. Because free-spinning nozzles are designed with high-quality, sturdy materials, they can withstand extremely hot temperatures. These nozzles are compact, allowing for a range of uses. Some common uses for Class Two free-spinning nozzles include the application of foam and barrel or canister cleaning. FDA-compliant nozzles are utilized for contact with food applications. Class Three free-spinning systems are primarily used for medium soiling, delivering good impact with jet nozzles.

Controlled rotation: Controlled rotation nozzles are found in Class Four. These high intensity systems are implemented for medium to heavy soiling jobs. They are available in various spray angles/ flow rates and are all FDA-compliant. These nozzles are controlled by an internal turbine containing no gears, ensuring that the speed remains in the optimum range, even at higher pressures.

Many controlled rotation nozzles are compatible with the Lechler rotation monitoring sensor, making it easy to oversee the cleaning process. The rotation monitoring sensor records the quantity of liquid flowing over the sensor tip. The sensor can be adjusted according to the tank size, pressure requirement, and specific nozzle.

Gear-controlled: Placed in Class Five, gear-controlled nozzles are perfect for removing difficult soils in tanks of any size. The solid jet nozzles mounted on the spray head produce powerful jets. Gear-controlled nozzles can operate in every direction, withstand high temperatures, and work in tandem with rotation monitoring sensors.

Connection Options

Every nozzle must be connected to a supply line. Lechler provides various solutions for differing applications: threaded connection, slip-on connection, Tri-Clamp, and welded connection. A threaded connection is formed by screwing a nozzle’s female thread onto a pipe’s male thread. Slip-on connections are often used in highly-sanitary environments. The nozzle is slipped onto the outer pipe and fastened with a pin or clamp. Frequently implemented in the food and beverage industry, Tri-Clamp connections can often be supplied with rotating cleaning nozzles. Finally, welded connections are especially suitable for applications with strict sanitary requirements.

TankClean Simulation Software

Understanding the available nozzle options is one challenge; planning for the perfect tank clean is another. Often, inspection alone is not enough. This is why we utilize a unique tank cleaning simulation software that allows you to visualize the tank cleaning process in real time.

How do we accomplish this? We replicate your specific tank geometry, select the right tank cleaning nozzle, and realistically simulate the spraying operation. Finally, we document the simulation results, including additional planning aids. TankClean is an excellent tool for the planning phase of new tanks, providing planning certainty, process optimization, process reliability, and cost and time savings. View an example of a TankClean demonstration!

Lechler: Engineering Your Spray Solution

At Lechler, we are willing and eager to help you with every step of the process. If you’re still unsure which tank cleaning nozzle to choose, contact us. We are happy to guide you, answering any questions and forming a custom solution designed to fit your unique application. Contact us today to request a TankClean simulation, to ask a specific question, or for more information!