The image above represents length of well screen.

To compute for length of well screen, three essential parameters are needed and these parameters are **Maximum Expected Discharge Capacity of Well (Q _{o}), Effective Open Area per Metre (A_{o}) and Entrance Velocity at the Screen (V_{e}).**

The formula for calculating length of well screen:

L = ^{Qo} / _{AoVe}

Where:

L = Length of Well Screen

Q_{o} = Maximum Expected Discharge Capacity of Well

A_{o} = Effective Open Area per Metre

V_{e} = Entrance Velocity at the Screen

Let’s solve an example;

Find the length of well screen when the maximum expected discharge capacity of well is 12, the effective open area per metre is 24 and the entrance velocity at the screen is 18.

This implies that;

Q_{o} = Maximum Expected Discharge Capacity of Well

A_{o} = Effective Open Area per Metre

V_{e} = Entrance Velocity at the Screen

L = ^{Qo} / _{AoVe}

L = ^{12} / _{(24)(18)}

L = ^{12} / _{432}

L = 0.027

Therefore, the **length of well screen **is **0.027.**

**Calculating the Maximum Expected Discharge Capacity of Well when the Length of Well Screen, the Effective Open Area per Metre and the Entrance Velocity at the Screen is Given.**

Q_{o} = L x (A_{o}V_{e})

Where;

Q_{o} = Maximum Expected Discharge Capacity of Well

L = Length of Well Screen

A_{o} = Effective Open Area per Metre

V_{e} = Entrance Velocity at the Screen

Let’s solve an example;

Find the maximum expected discharge capacity of well with a length of well screen as 21, effective open area per metre as 10 and entrance velocity at the screen as 5.

This implies that;

L = Length of Well Screen = 21

A_{o} = Effective Open Area per Metre = 10

V_{e} = Entrance Velocity at the Screen = 5

Q_{o} = L x (A_{o}V_{e})

Q_{o} = 21 x (10 x 5)

Q_{o} = 21 x 50

Q_{o} = 1050

Therefore, the **maximum expected discharge capacity of well **is **1050.**

**Calculating the Effective Open Area per Metre when the Length of Well Screen, the Maximum Expected Discharge Capacity of Well and the Entrance Velocity at the Screen is Given.**

A_{o} = ^{(Qo / L)} / _{Ve}

Where;

A_{o} = Effective Open Area per Metre

L = Length of Well Screen

Q_{o} = Maximum Expected Discharge Capacity of Well

V_{e} = Entrance Velocity at the Screen

Let’s solve an example;

Find the Effective Open area per metre when the length of well screen is 15, the maximum expected discharge capacity of well is 30 and the entrance velocity at the screen is 3.

This implies that;

L = Length of Well Screen = 15

Q_{o} = Maximum Expected Discharge Capacity of Well = 30

V_{e} = Entrance Velocity at the Screen = 3

A_{o} = ^{(Qo / L)} / _{Ve}

A_{o} = ^{(30 / 15)} / _{3}

A_{o} = ^{2} / _{3}

A_{o} = 0.67

Therefore, the **effective open area per metre** is **0.67.**

**Calculating the Entrance Velocity at the Screen when the Length of Well Screen, the Maximum Expected Discharge Capacity of Well and the Effective Open Area per Metre is Given.**

V_{e} = ^{(Qo / L)} / _{Ao}

Where;

V_{e} = Entrance Velocity at the Screen

L = Length of Well Screen

Q_{o} = Maximum Expected Discharge Capacity of Well

A_{o} = Effective Open Area per Metre

Let’s solve an example;

Given that the length of well screen is 6, the maximum expected discharge capacity of well is 24 and the effective open area per metre is 2. Find the entrance velocity at the screen?

This implies that;

L = Length of Well Screen = 6

Q_{o} = Maximum Expected Discharge Capacity of Well = 24

A_{o} = Effective Open Area per Metre = 2

V_{e} = ^{(Qo / L)} / _{Ao}

V_{e} = ^{(24 / 6)} / _{2}

V_{e} = ^{4} / _{2}

V_{e} = 2

Therefore, the **entrance velocity **is **2.**

Nickzom Calculator – **The Calculator Encyclopedia** is capable of calculating the length of well screen.

To get the answer and workings of the length of well screen using the **Nickzom Calculator – The Calculator Encyclopedia. **First, you need to obtain the app.

You can get this app via any of these means:

**Web** – https://www.nickzom.org/calculator-plus

To get access to the **professional **version via web, you need to **register** and **subscribe **for** NGN 1,500 **per** annum** to have utter access to all functionalities.

You can also try the **demo **version via https://www.nickzom.org/calculator

**Android (Paid)** – https://play.google.com/store/apps/details?id=org.nickzom.nickzomcalculator

**Android (Free)** – https://play.google.com/store/apps/details?id=com.nickzom.nickzomcalculator

**Apple (Paid)** – https://itunes.apple.com/us/app/nickzom-calculator/id1331162702?mt=8

Once, you have obtained the calculator encyclopedia app, proceed to the **Calculator Map, **then click on **Agricultural **under **Engineering****.**

Now, Click on **Water Budget **under **Agricultural**

Now, Click on **Length of Well Screen**** **under **Water Budget**

The screenshot below displays the page or activity to enter your values, to get the answer for the length of well screen according to the respective parameters which are the **Maximum Expected Discharge Capacity of Well (Q _{o}), Effective Open Area per Metre (A_{o})** and

**Entrance Velocity at the Screen (V**

_{e}).Now, enter the values appropriately and accordingly for the parameters as required by the **Maximum Expected Discharge Capacity of Well (Q _{o})** is

**12**,

**Effective Open Area per Metre (A**is

_{o})**24**and

**Entrance Velocity at the Screen (V**is

_{e})**18**.

Finally, Click on Calculate

As you can see from the screenshot above, **Nickzom Calculator**– The Calculator Encyclopedia solves for the length of well screen and presents the formula, workings and steps too.