The image above represents rated static head (in bottom gating).

To compute for rated static head, two essential parameters are needed and these parameters are **Height of the Sprue from its Top to the Point of Metal Entry into the Mould Cavity (H)** and **Height of the Casting (C).**

The formula for calculating rated static head (in bottom gating).

H_{s} = H – ^{C} / _{2}

Where:

H_{s} = Rated Static Head (in Bottom Gating)

H = Height of the Sprue from its Top to the Point of Metal Entry into the Mould Cavity

C = Height of Casting

Let’s solve an example;

Find the rated static head (in bottom gating) when the height of the sprue from its top to the point of metal entry into the mould cavity is 11 and the height of casting is 8.

This implies that;

H = Height of the Sprue from its Top to the Point of Metal Entry into the Mould Cavity = 11

C = Height of Casting = 8

H_{s} = H – ^{C} / _{2
}H_{s} = 11 – ^{8} / _{2}

H_{s} = 11 – 4

H_{s} = **7**

Therefore, the **rated static head (in bottom gating)** is **7 m.**

**Calculating the Height of the Sprue from its Top to the Point of Metal Entry into the Mould Cavity when the Rated Static Head (in bottom gating) and the Height of Casting is Given.**

H = H_{s} + ^{C} / _{2}

Where;

H = Height of the Sprue from its Top to the Point of Metal Entry into the Mould Cavity

H_{s} = Rated Static Head (in Bottom Gating)

C = Height of Casting

Let’s solve an example;

Find the height of the sprue from its top to the point of metal entry into the mould cavity when the rated static head is 22 and the height of casting is 8.

This implies that;

H_{s} = Rated Static Head (in Bottom Gating) = 22

C = Height of Casting = 8

H = H_{s} + ^{C} / _{2}

H = 22 + ^{8} / _{2}

H = 22 + 4

H = 26

Therefore, the **height of the sprue from its top to the point of metal entry into the mould cavity **is **26 m.**

**Calculating the Height of Casting when the Rated Static Head (in bottom gating) and the Height of the Sprue from its Top to the Point of Metal Entry into the Mould Cavity is Given.**

c = – (H_{s} – H) 2

Where;

C = Height of Casting

H_{s} = Rated Static Head (in Bottom Gating)

H = Height of the Sprue from its Top to the Point of Metal Entry into the Mould Cavity

Let’s solve an example;

Find the height of casting when the rated static head is 40 and the height of the sprue from its top of the point of metal entry into the mould cavity is 24.

This implies that;

H_{s} = Rated Static Head (in Bottom Gating) = 40

H = Height of the Sprue from its Top to the Point of Metal Entry into the Mould Cavity = 24

c = – (H_{s} – H) 2

c = – (40 – 24) 2

c = – (16) 2

c = – 32

Therefore, the **height of casting **is **– 32 m.**

Nickzom Calculator – **The Calculator Encyclopedia** is capable of calculating the rated static head (in bottom gating).

To get the answer and workings of the rated static head (in bottom gating) 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 **Materials & Metallurgical**** **under **Engineering****.**

Now, Click on **Foundry Technology**** u**nder **Material & Metallurgical**

Now, Click on **Design of Gating System **under **Foundry Technology**

Now, Click on **Rated Static Head (in bottom gating)**** **under **Design of Gating System**

The screenshot below displays the page or activity to enter your values, to get the answer for the rated static head (in bottom gating) according to the respective parameters which are the **Height of the Sprue from its Top to the Point of Metal Entry into the Mould Cavity (H)** and **Height of the Casting (C).**

Now, enter the values appropriately and accordingly for the parameters as required by the **Height of the Sprue from its Top to the Point of Metal Entry into the Mould Cavity (H) **is **11** and **Height of the Casting (C)** is **8**.

Finally, Click on Calculate

As you can see from the screenshot above, **Nickzom Calculator**– The Calculator Encyclopedia solves for the rated static head (in bottom gating) and presents the formula, workings and steps too.