1、最小流量：在正常情況下，泵不允許在Qmin線以左范圍內(nèi)運行。泵短時間內(nèi)允許小流量運行，最小流量為0．05倍設計點流量，但不超過5分鐘，任何更長時間運行都將造成泵內(nèi)過熱。不管怎樣，在這種小流量情況下，會影響泵的結(jié)構(gòu)和系統(tǒng)，導致?lián)P程的變化。如果泵在系統(tǒng)中運行，而系統(tǒng)的凈揚程是總揚程的主要部分，或并聯(lián)運行，或考慮到變轉(zhuǎn)速運行，那么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必須大于NPSHR一個余量值。
3、揚程和性能參數(shù)適用于P為1.Okg/dm³和粘度不大于20mm²/S介質(zhì)，如密度不足1.0，功率是ρ的倍數(shù)：
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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.
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