Draining water from hydrocarbon storage tanks -

4 Advantages of Automated vs Manual Operation

1. Dewatering hydrocarbon product storage tanks prevents microbial growth

Draining accumulated water from hydrocarbon storage tanks is one of the important tasks in the operation of hydrocarbon tank terminals. As discussed in our article 3 Critical Reasons for Dewatering Hydrocarbon Products Storage Tanks, accumulated water in hydrocarbon products' storage tanks cause the following:

  • Corrosion, requiring frequent and costly maintenance to tanks and pipes

  • Damage to hydrocarbon product due to "diesel bug" layer

  • Interference measuring the amount of product in the tank, thus resulting inaccurate measurement data

  • Occupy space inside the tank which should be used to store product



This picture shows crude oil environmental contamination due to manual draining. However, this is also with manual draining of refined hydrocarbon products, which is colorless and clear, and therefore less visible.

Still, in the 21st century this process is conducted manually by Operators opening the drain valve and closing it when they see the appearance of hydrocarbon product in the water. Manual draining of water from storage tanks is a complicated and cumbersome process, and therefore, may not be conducted frequently enough. Infrequent draining may cause serious damage to the hydrocarbon product stored inside the tank. Furthermore, manual draining may result product loss of estimated value of 30,000 USD per tank, per year. This cost may be saved by self-operated automatic draining valve


  1. Automated dewatering saves costs of "Dead Leg" 

At the end of every dewatering session, the drain line is full of hydrocarbon products. At the beginning of the next draining session, this amount of product called ''Dead Leg'', needs to be drained from the drain pipe first, so that the accumulated water could be drained. This "Dead Leg" is "lost" in the sump.

The cost of ''Dead Leg'' loss per year, per single storage tank, is estimated to be as high as 10,000 USD (*as per March 2022 oil prices). For example, a hydrocarbon storage tank which is manually drained of the accumulated water 4 times a month,

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with draining pipe diameter of 6" and length of 25 meters, may lose 21,800 liters a year. Furthermore, the cost of re-processing the "Dead Leg" (usually several different types of hydrocarbon) substantial and needs to be taken into consideration as well.

By using automatic draining valve, equipped with a pump, the Operator is able to pump the ''Dead Leg'' of Hydrocarbon product, trapped in the draining line, back to the storage tank. Thus, preventing costly loss of hydrocarbon product, and the need for re-processing.

 2. Automated dewatering saves cost of Hydrocarbon product loss due to undetected water-product transition point

One of the setbacks of manual draining operation is the difficulty assessing the exact water-hydrocarbon product transition point, meaning when all the water has drained and hydrocarbon product starts to drain.

During manual drainage session, the operator must be present for the duration of the entire process,

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monitoring for any hydrocarbon product leakage to prevent product loss. The Operator does that by visual checks to observe the water/hydrocarbon product change, and by the sense of smell. This may result fair quantities of hydrocarbon product spilled to the sump. This amount depends on the professional level and training of the Operator, and on Operator's experience.

It is estimated that dewatering by vastly experienced Operator may lose 50 liters of product on average per single drain, while dewatering by a less experienced operator may even result a loss of more than 200 liters per single drain.  This amount of product loss per year from a single tank may reach 5,000 liters and even more. In terms of costs, this amount of product loss is valued at not less than 4,000 USD per tank, per year (* as per March 2022 oil prices).

However, during automated dewatering process, when all the accumulated water has drained from the storage tank, the TOO Separation draining valve senses the presence of product and immediately shuts off, drip tight, preventing any hydrocarbon product spills and costly expenses.

    3.   Automated dewatering saves cost of Hydrocarbon product loss due to Vortex

Vortex may formulate inside the storage tank during manual draining when opening the draining valve fully-open. This may create high flow, and could causes Vortex within the tank, mixing hydrocarbon product with the drained water. Even partially opening the draining valve may create Vortex. It is estimated that hydrocarbon product loss due to Vortex is about 2.5%-5% of the amount of water drained, per single drain, depending on the experience and training of the Operator. That may amount to a minimum of 2,400 liters per year, per single tank, for draining volume of 2000 liters and 4 draining sessions per month. And product loss of 2,040 USD per year per single tank.

By using a TOO Separation draining valve with built-in anti-vortex, the draining flow is limited and therefore does not allow even the first drop of oil to be drained.

   4.  Automated dewatering prevents Health risk to Operators

The Operator is exposed throughout the lengthy manual dewatering process to toxic fumes. Furthermore, tanks with an apex-up bottom configuration may need to be drained at more than one point, which makes the manual draining process even lengthier. Many of the gases emitted during the dewatering process are harmful to humans and can cause respiratory problems.


Using TOO Separation draining valve eliminates the utter most of the toxic fumes emitted during manual dewatering

There are additional cost savings as a result of using automated dewatering. The accurate amount of USD for these costs is dependent on terminals' activities. These additional cost savings include:

  • Cost of maintenance of equipment and systems (water-fuel separator, filters, electricity to pumps, transportation)

  • Cost of manpower resources which could be redirected to other projects for creating a more efficient workflow

However, the most important advantages of automated dewatering is transforming the complex and cumbersome manual operation into an efficient and effective task that may be performed easily and daily

These are only some of the advantages of automated draining of water from hydrocarbon product's storage tanks, compared to manual draining. Substantial losses – both in product volume and in costs -  could be avoided by using Eco-Valves' automated TOO valve for efficient and safe draining of water from hydrocarbon storage tanks.  Furthermore, refineries and tank terminals may save on maintenance expenses, avoid costs of lawsuits due to environmental harm and health risks, and gain a safe and clean environment for Operators to work in. this makes using automated draining valve a win-win case.