\begin{tabular}{ll} QUESTION 4 (PUMPS) \ 4.1 & Give THREE moving parts of a reciprocating pump. \ 4.2 & $$ \begin{array}{l} ext { List THREE advantages of a pump with external packing. } \ ext { What is the difference between the flooding head and suction head, support your } \ ext { answer by means of a sketch. }\end{array} $$ \ \hline 13$$ ) $$\end{tabular}

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\begin{tabular}{ll} QUESTION 4 (PUMPS) \ 4.1 & Give THREE moving parts of a reciprocating pump. \ 4.2 & $$ \begin{array}{l}	ext { List THREE advantages of a pump with external packing. } \ 	ext { What is the difference between the flooding head and suction head, support your } \ 	ext { answer by means of a sketch. }\end{array} $$ \ \hline 13$$ ) $$\end{tabular}

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**4.1 Three Moving Parts of a Reciprocating Pump**

1. **Piston (or Plunger):** The piston moves back and forth to create the pressure difference that leads to fluid movement.  
2. **Connecting Rod:** This links the piston to the crank mechanism, converting rotary motion into reciprocating motion.  
3. **Check (Suction/Discharge) Valves:** These open and close alternately to allow fluid to enter and exit the pumping chamber as needed.

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**4.2 Advantages of a Pump with External Packing**

1. **Ease of Maintenance and Packing Replacement:** External packing is accessible and can be adjusted or replaced without extensive disassembly of the pump.
2. **Improved Cooling:** Since the packing is located on the outside, it is more easily exposed to the cooling medium (usually air), which helps dissipate heat.
3. **Reduced Friction and Wear:** External packing allows for easier adjustment of the packing pressure, which can minimize wear on both the packing and the shaft.

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**Difference Between Flooding Head and Suction Head**

- **Flooding Head:**  
  The flooding head is the vertical distance between the pump’s centerline (or the suction inlet) and the free surface level of the liquid (flooded condition). It represents the external head available due to the submergence of the pump inlet in a liquid reservoir. Essentially, it indicates the degree to which the pump is “flooded” and helps ensure that the pump readily receives liquid.

- **Suction Head:**  
  The suction head, on the other hand, is the effective head (or pressure) at the pump’s suction side. This head is calculated by taking into account the vertical distance from the free surface to the pump suction inlet, along with losses due to friction in the suction line (and in some cases, corrections for vapor pressure if any suction lift is involved). It is the actual pressure head available for the pumping mechanism to work against.

**Sketch:**

$$
\begin{array}{c}
\text{Flooding Level (Free Surface)} \
\bigg|\text{Flooding Head } (H_f)\bigg| \
\hline \
\text{Pump Suction Inlet} \
\bigg|\text{Suction Head } (H_s) \bigg| \
\text{Pump Centerline}
\end{array}
$$

In this sketch, the flooding head $$ H_f $$ is the vertical distance from the free liquid surface down to the pump suction inlet, ensuring that the pump is fully flooded. The suction head $$ H_s $$ represents the effective head (after accounting for losses) that delivers the required pressure to the pump for its operation.
**4.1 Three Moving Parts of a Reciprocating Pump** 1. **Piston (or Plunger):** Moves back and forth to create pressure. 2. **Connecting Rod:** Links the piston to the crank, converting motion. 3. **Check (Suction/Discharge) Valves:** Allow fluid to enter and exit the pump. --- **4.2 Advantages of a Pump with External Packing** 1. **Easy Maintenance:** Packing can be replaced without major disassembly. 2. **Better Cooling:** Packing is exposed to cooling air, reducing heat. 3. **Reduced Friction:** Easier adjustment of packing pressure minimizes wear. --- **Difference Between Flooding Head and Suction Head** - **Flooding Head:** Vertical distance from the free liquid surface to the pump inlet, ensuring the pump is fully submerged. - **Suction Head:** Effective head available at the pump’s suction side, accounting for vertical distance and losses in the suction line. **Sketch:** $$ \begin{array}{c} \text{Free Liquid Surface} \ \bigg|\text{Flooding Head } (H_f)\bigg| \ \hline \ \text{Pump Suction Inlet} \ \bigg|\text{Suction Head } (H_s) \bigg| \ \text{Pump Centerline} \end{array} $$ In the sketch, $$ H_f $$ ensures the pump is fully flooded, while $$ H_s $$ represents the effective pressure head available for pumping.

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