The image above represents relative freezing time.

To compute for relative freezing time, four essential parameters are needed and these parameters are **Constant (L), Constant (C), Volume of Riser/Volume of Casting (y) **and **Relative Contraction of Freezing (B).**

The formula for calculating relative freezing time:

x = ^{L} / _{y – B} + C

Where:

x = Relative Freezing Time

y = Volume of Riser / Volume of Casting

B = Relative Contraction on Freezing

C = Constant

L = Constant

Let’s solve an example;

Find the relative freezing time when the volume of riser/volume of casting is 26, the relative contraction on freezing is 21, the constant is 8 and the constant is 11.

This implies that;

y = Volume of Riser / Volume of Casting = 26

B = Relative Contraction on Freezing = 21

C = Constant = 11

L = Constant = 8

x = ^{L} / _{y – B} + C

x = ^{8} / _{26 – 21} + 11

x = ^{8} / _{5} + 11

x = 1.6 + 11

x = **12.6**

Therefore, the **relative freezing time **is **12.6 s.**

**Calculating the Constant (L) when the Relative Freezing Time, Constant (C), the Volume of riser/Volume of Casting and the Relative Contraction on Freezing is Given.**

L = x (y – B) – C

Where;

L = Constant

x = Relative Freezing Time

y = Volume of riser / Volume of Casting

B = Relative Contraction on Freezing

C = Constant

Let’s solve an example;

Find the Constant when the relative freezing time is 24, the volume of riser / volume of casting is 14, the relative contraction on freezing is 8 and the constant is 10.

This implies that;

x = Relative Freezing Time = 24

y = Volume of riser / Volume of Casting = 14

B = Relative Contraction on Freezing = 8

C = Constant = 10

L = x (y -B) – C

L = 24 (14 – 8) – 10

L = 24 (6) – 10

L = 144 – 10

L = 134

Therefore, the **constant **is **134.**

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