The valves on heating pipes are typically ball valves or gate valves. Ball valves have a spherical disc inside that controls the flow of water by rotating the handle, while gate valves have a gate or wedge that moves up and down to control the flow. Both types of valves are used to regulate the flow of hot water through the heating system and can be manually operated to adjust the temperature or shut off the flow completely. **

No, Russia does not extradite North Korean refugees to North Korea. Russia is a signatory to the 1951 Refugee Convention and its 1967 Protocol, which prohibits the refoulement of refugees to their home country where they may face persecution. As a result, Russia generally provides protection to North Korean refugees and does not send them back to North Korea. However, the situation for North Korean refugees in Russia can still be difficult, as they often face challenges in obtaining legal status and may be at risk of deportation to third countries. **

The North Sea is not called the North Ocean because it does not meet the criteria to be classified as an ocean. Oceans are larger and deeper bodies of saltwater that cover a significant portion of the Earth's surface, while the North Sea is a relatively small and shallow sea located between the United Kingdom, Norway, Denmark, Germany, and the Netherlands. Additionally, oceans are typically separated by continents, while the North Sea is connected to the Atlantic Ocean. Therefore, the North Sea is appropriately named a sea rather than an ocean. **

North Africans are a diverse group of people with a range of ethnicities and skin tones. While some North Africans may have darker skin and identify as black, others may have lighter skin and identify as white or another race. It is important to recognize that race is a social construct and can vary depending on cultural and historical contexts. Ultimately, it is up to individuals to self-identify their race and ethnicity. **

The choice between Allgäu and the North Sea depends on personal preferences and interests. Allgäu, located in southern Germany, offers picturesque landscapes, charming villages, and outdoor activities such as hiking and skiing. On the other hand, the North Sea, located in northern Germany, provides a different experience with its coastal scenery, sandy beaches, and opportunities for water sports and relaxation by the sea. Ultimately, the decision between Allgäu and the North Sea will depend on whether you prefer mountainous regions or coastal areas for your vacation. **

The North Sea offers a variety of vacation sights for travelers to enjoy. Some popular attractions include the stunning beaches of the North Sea coast, where visitors can relax, swim, and participate in water sports. The region is also known for its charming seaside towns and villages, where visitors can explore historic sites, enjoy fresh seafood, and browse local shops. Nature lovers can take advantage of the many hiking and cycling trails that wind through the picturesque coastal landscapes of the North Sea. **

North Hesse, Germany, is home to a variety of sights worth exploring. Visitors can admire the stunning architecture of Kassel's Bergpark Wilhelmshöhe, a UNESCO World Heritage Site featuring a magnificent palace and cascading water features. Nature lovers can enjoy the picturesque landscapes of the Habichtswald Nature Park, perfect for hiking and outdoor activities. Additionally, the Grimmwelt Kassel museum offers a fascinating insight into the lives and works of the Brothers Grimm, famous for their fairy tales. **

"North by Northwest" is a classic thriller film directed by Alfred Hitchcock and released in 1959. The film follows the story of a man named Roger Thornhill, played by Cary Grant, who is mistaken for a government agent and gets caught up in a web of espionage, mistaken identity, and danger. The film is known for its iconic scenes, suspenseful plot, and clever twists, and is considered one of Hitchcock's best works. **