tube is water, water surfaces of the three equipments are at the same level. Try to determine 1)Are the pressures equal to each other at the points of 1, 2, 3? 2)Are the pressures equal to each other at the points of 4, 5, 6? 3)If h1=100mm, h2=200mm, and the equipment A is open to the atmosphere(the tmospheric pressure is 760mmHg), try to calculate the pressures above the water in the equipment B and C Solution: I) The pressure is different among 1, 2 and 3. They are at the same level plane of static liquid, but they don t connect the same liquid 2)The pressure is the same among 4, 5 and 6. They are at the same level plane of atic liquid, and they connect the same liquid 3)∵P4=P +Puzogh,=PB+PRog(,-h,)+pu Pe=P-(pHe-Puzo)gh, =101330—(13600-1000)×981×0.1 88970N/m2 or P:=12360N/m2(vacuum se P4= p6 then PA+ PH2ogh2=Pc+ PHggh2 P=Pu-(PHg-PH2o)gh2 =101330—(13600-1000)×9.81×0.2 =76610N/m or P=24720N/m2(vacuum degree 6. As shown in the figure, measure the steam pressure above the boiler by the series U-shape differential pressure meter, the indicating liquid of the differential pressure meter is mercury, the connected tube between the two"U -shape meters is full of water. Given that the distance between the mercury levels and the referring level are h1=2.3m, h2=1.2mtube is water, water surfaces of the three equipments are at the same level. Try to determine: 1) Are the pressures equal to each other at the points of 1,2,3? 2) Are the pressures equal to each other at the points of 4,5,6? 3) If h1=100mm，h2=200mm，and the equipment A is open to the atmosphere(the atmospheric pressure is 760mmHg),try to calculate the pressures above the water in the equipment B and C. Solution: 1) The pressure is different among 1, 2 and 3. They are at the same level plane of static liquid, but they don’t connect the same liquid. 2) The pressure is the same among 4, 5 and 6. They are at the same level plane of static liquid, and they connect the same liquid. 3)  p4 = p5 then 2 2 2 2 1 1 pA + pH O gh = pB +  H O g(h − h ) +  Hg gh 2 1  pB = pA − ( Hg −  H O )gh =101330―（13600―1000）×9.81×0.1 =88970N/m² or pB =12360N/m²（vacuum） and because p4 = p6 then pA +  H 2O gh2 = pC +  Hg gh2 so pc = 2 2 p A − ( Hg −  H O )gh =101330―（13600―1000）×9.81×0.2 =76610N/m² or pc = 24720N/m²（vacuum degree） 6. As shown in the figure, measure the steam pressure above the boiler by the series “U”-shape differential pressure meter, the indicating liquid of the differential pressure meter is mercury, the connected tube between the two “U ”-shape meters is full of water. Given that the distance between the mercury levels and the referring level are h1=2.3m，h2=1.2m