Calculation Of minimum Inlet Pressure

If the pressure in pump is lower than the vapour pressure of medium, cavitation will occur, which will affect the performance of pump. To avoid the cavitation and ensure the pump inlet has a minimum pressure, maximum suction head should be calculated as following:

H = Pbx10.2-NPSH-Hf-hv-Hs

Pb: Pressjoni atmosferika, bar (F'sistema ta 'pajpijiet viċin, tista' titqies bħala l-pressjoni tas-sistema);
NPSH: Net positive suction head, m (Value at maximum flow of Q-NPSH curve);
Hf: Suction pipe line loss (Value at maximum flow of corresponding pipeline);
Hv: Medium vapour pressure, m (Medium vapour pressure at corresponding temperature, the default medium is water, as shown in figure4 on the right );
Hs: Il-marġini tas-sigurtà, m, il-valur ġenerali huwa 0.5.
Riżultat tal-kalkolu: jekk H huwa pożittiv, il-pompa tiġi installata fil-mod ta 'ġbid tal-arja, inkella tkun installata b'mod' downdraft '.

Note: It is not necessary to do above calculation under general conditions. Only when we use pump in the following situations do we need to calculate the H:
1. It-temperatura medja hija għolja;
2.The velocity of flow is larger than rated value;
3.Suction head is big or inlet pipeline is long;
4.System pressure is small;
5.Inlet condition is bad.

Selection Of Pumps

Selection of pumps should be based on:
Duty point of the pump.
Dimensional data such as pressure loss as aresult of height differences,friction loss in the pipework,
Effiċjenza tal-pompa eċċ.
Materjali tal-pompa
Konnessjonijiet tal-pompa
Tabelli tal-konfigurazzjoni tas-siġill mekkaniku użat komunement

1. Duty point of the pump:

Minn punt ta 'xogħol huwa possibbli li tagħżel pompa fuq il-bażi tal-kurvi tal-kurva murija f' "kurvi tal-prestazzjoni / tekniċi" data.

2. Dimensional data:

Meta tingħata daqs pompa dan li ġej għandu jittieħed kontabilità: “Fluss meħtieġ u pressjoni fil-punt tat-tluq.” Telf ta 'pressjoni bħala riżultat ta' differenzi fl-għoli. għal Fig.1) Jista '"L-aħjar effiċjenza fil-punt tad-dazju stmat." Valur NPSH. "Għall-kalkolu tal-valur NPSH, ara l-kurva korrispondenti tal-kurva.

3. Pump efficiency:

Qabel ma jiġi ddeterminat l-aħjar punt ta 'effiċjenza, il-parti operattiva tal-pompa għandha tiġi identifikata. Jekk il-pompa mistennija taħdem bħala l-istess punt ta 'xogħol, imbagħad agħżel pompa BL li tkun qed taħdem f'punt ta' xogħol li tikkorrispondi ma 'l-aħjar effiċjenza tal-pompa.
Billi l-pompa hija mkejla fuq il-bażi ta 'l-ogħla fluss possibbli, huwa importanti li dejjem ikollha l-punt tad-dazju fuq il-lemin fuq il-kurva ta' effiċjenza (eta) sabiex l-effiċjenza tinżamm għolja meta l-fluss jinżel.

4. Pump material:

Selection of pump connection depend on the rated pressure and pipe work. the pump offer a wide range of ftexible connection such as:

5. Commonly used mechanical seal configuration tables

Application Field

Shaft seal type

Materjal li jissiġilla x-xaft

Normal

Special

1

2

3

4 5

Type key

Parti li ddur

Kodiċi

Parti wieqfa

Kodiċi

Elastomeri

Kodiċi

Compression spring

Kollor

Kodiċi

0a sa + 90a 'ilma nadif

â—

Graphite

A

SiC

S

FPM

F

SUS304

Ċ

ASFC

0a sa + 90a 'ilma nadif

â—

WC

W

Graphite

A

FPM

F

SUS304

Ċ

WAFC

Reżistenza għall-korrużjoni + 90a sa + 120 °

â—

SiC

S

SiC

S

EPDM

E

SUS304

Ċ

SSEC

up to 0℃

â—

WC

W

WC

W

EPDM

E

SUS304

Ċ

WWEC

Mechanical seal type	Mudell tal-pompa	d1	d2	h
NJK	BL(T)2/4	12	12	55
	BL (T) 8/12/16/20	16	16	57.5
	BL(T)32/45/60/90	22	22	72
NDA	BW(J)2/4	12.7	16	32
	BW(J)8/16	17.4	20	33.5