1、最小流量：在正常情況下，泵不允許在（zài）Qmin線以左範圍（wéi）內運行。泵短時間內允許（xǔ）小流量運行，最小流量（liàng）為0．05倍設計點流量，但不超過（guò）5分鍾，任何更長時間運行都將（jiāng）造成泵內過熱。不管怎樣，在這種小流量情況下，會影響泵的結構和係統，導致揚程的變化。如（rú）果（guǒ）泵在係（xì）統中運行（háng），而係統的淨揚程是總揚程的主要部分，或並聯（lián）運行，或考（kǎo）慮到變轉速運行，那麽這種揚程的變化是不可忽視的。

  2、最大流量：工作極限由NPSHR決定，而NPSHA必（bì）須大於NPSHR一個餘量值（zhí）。

  3、揚程和性能（néng）參數適用於P為1.Okg/dm³和粘（zhān）度不大於20mm²/S介質，如密度（dù）不足1.0，功率是ρ的倍數：

bearings, the correct oil level must be verified at regular.

  7). If the flexible coupling elements begin to show signs of wear, they should be replaced in due time.

  8). If the liquid for sealing, cooling and lubricating is taken from an external source,  the pressure must be 1.0 to 2.0 bar higher than at the  suction nozzle. The gland packing(if the pump is fitted with one)  should drip slightly during operation. The gland should only be gently tightened.

  3. Stopping

  1) . While stopping the pump running, first turn off the brake valve on the discharge pipe passage way.

  2). Close the auxiliary connections. The shaft seal in pumps where the liquid is fed in under vacuum must also be lubricated with sealing liquid during standstill.

  3). In the event of frost and/or prolonged shutdowns, the pump and if applicable the cooling chambers must be drained or otherwise protected against freezing.

  4). Pumps handling liquids posing health hazards must be drecontaminated. When draining the edium see to it that there is no risk to persons or the environment.

  Explanations

  a. Minimum flow:

  In normal service the pumps should not be operated to the left of the line indicating Qmin. Lower flows,  up to 0.05×Qoptimum,  are permissible for short periods of up to 5 minutes. Any longer operation will cause overheating within the pump. However, at these lower flows the influence of the system as well as the pump configuration may cause the pump head to vary. Such head variations are significant if the pump is to operate in a system where the static head is a major portion of the total head or parallel or variable speed operation is to be considered.

  b. Maximum flow

  The limit of operation is given by the NPSHR characteristic with the indicated margins relative toNPSHA.

  c. The total heads and the performance characteristics refer to mediums compressed with p = 1.0 kg/dm³ and kinematic viscosity up to 20mm²/s. If the density is not 1.0, the performance characteristics are to be multiplied by ρ.