1.
The double eccentric principle is so named due to...?
Correct Answer
C. The valve shaft being offset from the centre along 2 axis.
Explanation
The double eccentric principle is named because the valve shaft is offset from the center along two axes. This means that the valve opens and closes in a way that is not directly in line with the center of the valve, allowing for a more efficient and effective sealing system. This design reduces friction and wear on the valve, resulting in a longer lifetime compared to competitors' valves.
2.
PN ___ is the highest pressure rating for which the series 756 can be offered.
Correct Answer
16
Sixteen
Explanation
The correct answer is "16, Sixteen." This means that the highest pressure rating for which the series 756 can be offered is 16.
3.
The plate disc design series 756 butterfly valve is available in the following size ranges:
Correct Answer
C. 200 - 2200
Explanation
The correct answer is 200 - 2200. This answer is correct because it falls within the given size ranges of the plate disc design series 756 butterfly valve. The other size ranges mentioned in the question do not include the number 2200, so they are not the correct answer.
4.
The series 756 butterfly valve has a tilted disc design. What does this mean?
Correct Answer
C. When the valve is fully closed the disc is a few degrees off from being parallel to the valve face.
Explanation
The correct answer means that when the valve is fully closed, the disc is not perfectly parallel to the valve face but is tilted by a few degrees. This design feature allows for a tighter seal when the valve is closed, preventing any leakage.
5.
Which one of the following is an advantage of the series 756 butterfly valve compared to VAG and Erhard butterfly valves?
Correct Answer
D. All of the above.
Explanation
The series 756 butterfly valve has several advantages compared to VAG and Erhard butterfly valves. Firstly, it is equipped with rubber components from AVK Gummi, which ensures high-quality and reliable sealing. Additionally, the valve has a lower weight, making it easier to handle and install. Lastly, it is designed to reduce wear on the rubber sealing, increasing its lifespan and minimizing maintenance requirements. Therefore, the correct answer is "All of the above."
6.
What are the advantage of the fixated disc design?
Correct Answer
A. It eliminates the possibility of disc flutter.
Explanation
The advantage of the fixated disc design is that it eliminates the possibility of disc flutter. Disc flutter refers to the vibration or movement of a disc, which can cause disruptions or errors in its performance. By using a fixated disc design, any potential flutter is prevented, ensuring a stable and reliable operation.
7.
What is the difference between the seal on series 756 butterfly valve between DN 200-600 and DN 700-2200.
Correct Answer
C. The shape of the rubber seal and the retaining ring.
Explanation
The correct answer is that the difference between the seal on the series 756 butterfly valve between DN 200-600 and DN 700-2200 lies in the shape of the rubber seal and the retaining ring. This means that the design and structure of the seal and retaining ring vary between the two valve sizes. It is important to note that there are differences in the components used for sealing in the smaller and larger valves.
8.
Extensive cycle tests have been conducted showing no visible wear and tear on the seal of series 756 butterfly valve. How many operating cycles?
Correct Answer
B. 6000
Explanation
Based on extensive cycle tests, it has been observed that the seal of the series 756 butterfly valve does not show any visible wear and tear. The answer of 6000 operating cycles suggests that the valve has been tested for this number of cycles and has successfully maintained its integrity without any signs of damage or deterioration.
9.
The shaft sealing of a series 756 butterfly valve cannot be replaced under pressure?
Correct Answer
B. False
Explanation
Series 756 butterfly valves are available with a integral seat or with a stainless steel seat.
10.
What is the purpose of the locking device available on valves DN700-2200?
Correct Answer
D. It allows the disc to be locked in place temporarily for carrying out repairs or maintenance, such as the replacement of a gearbox.
Explanation
The locking device available on valves DN700-2200 allows the disc to be locked in place temporarily for carrying out repairs or maintenance, such as the replacement of a gearbox. This ensures that the valve remains in a fixed position during these procedures, preventing any accidental movement that could cause further damage or injury. It provides a secure and stable environment for the necessary maintenance work to be carried out effectively and safely.
11.
Which is an essential part of the high quality coating procedure used for the series 756 butterfly valve?
Correct Answer
D. All of the above.
Explanation
The high quality coating procedure used for the series 756 butterfly valve includes blast cleaning to ISO 12944-4, epoxy coating to DIN 30677-2 and GSK, and quality control procedures and audits. All of these components are essential in ensuring that the coating procedure meets the required standards and produces a high-quality end product. Blast cleaning helps to remove any contaminants from the surface, epoxy coating provides a protective layer, and quality control procedures and audits ensure that the coating process is consistently monitored and meets the necessary requirements. Therefore, all of the options listed are necessary for the high quality coating procedure.
12.
The 756 butterfly valve is available with the option of a stainless steel seat. The advantage is:
Correct Answer
D. It is replaceable and is ideal for high wear and tear systems.
Explanation
Series 756 butterfly valves are available with a integral seat or with a stainless steel seat.
13.
From DN700-1200 the series 756 butterfly valve is available with a flow-through disc design. What is the advantage of the flow-through disc?
Correct Answer
C. It is less sensitive to cavitation and offers lower headloss.
Explanation
The flow-through disc design of the series 756 butterfly valve has the advantage of being less sensitive to cavitation and offering lower headloss. This means that it is better able to handle situations where cavitation may occur, such as when there are rapid changes in pressure or flow rate. Additionally, the reduced headloss means that there is less resistance to the flow of fluid through the valve, resulting in improved efficiency.
14.
What is the difference between an IP67 and an IP68 gearbox?
Correct Answer
D. IP67 is for above ground use, IP68 is for below ground (submerged) use.
Explanation
The difference between an IP67 and an IP68 gearbox is that the IP67 gearbox is designed for above ground use, while the IP68 gearbox is specifically made for below ground or submerged use. This means that the IP68 gearbox has a higher level of protection against water and dust ingress compared to the IP67 gearbox, making it suitable for use in environments where it may be exposed to water or submerged in water.
15.
There are numerous reasons for using high quality rubber in butterfly valves for drinking water. Which is NOT a reason?
Correct Answer
A. EPDM is much easier to manufacture than almost all other types of rubber.
Explanation
EPDM is much easier to manufacture than almost all other types of rubber. This statement is NOT a reason for using high quality rubber in butterfly valves for drinking water. The other options provide valid reasons for using high quality rubber, such as resistance to common elements found in drinking water, excellent compression set, and approval for drinking water purposes.
16.
The series 756 butterfly valve is heavier than a gate valve of the same diameter?
Correct Answer
B. False
Explanation
The statement is false. A butterfly valve is generally lighter than a gate valve of the same diameter. This is because butterfly valves have a simpler design and use less material compared to gate valves. The weight of a valve depends on various factors such as the type of material used, the design, and the size. However, in general, butterfly valves tend to be lighter and more compact than gate valves.
17.
The series 756 butterfly valve is ideal for modulation purposes.
Correct Answer
B. False
Explanation
The statement suggests that the series 756 butterfly valve is not ideal for modulation purposes.
18.
A series 756 butterfly valve has higher headloss than a gate valve of the same diameter.
Correct Answer
A. True
Explanation
A butterfly valve typically has a higher headloss compared to a gate valve of the same diameter. This is because the design of a butterfly valve creates more resistance to the flow of fluid, resulting in higher headloss. Gate valves, on the other hand, have a more streamlined design that allows for smoother flow and lower headloss. Therefore, it is true that a series 756 butterfly valve has higher headloss than a gate valve of the same diameter.