Peristaltic pumps in the environmental marketplace

Peristaltic pumps in the environmental marketplace from Watson-Mar-low Bredel Pumps explains why one of the simplest pumping technologies - peristaltic pumps - has become one of the leading solutions in the municipal and industrial water treatment arena. He discusses the advantages of the technology and the reasons why the consulting engineering community has embraced it in a relatively short period of time.

T

he first commercially produced hose pumps were introduced in 1956, and many design improvements have been made along the way. As recently as ten years ago, peristaltic pumps were only sparsely found in water and wastewater treatment facilities in North America, primarily due to limitations with hose/tube design as well as pump capacity for both low and high flow applications. Over the last decade, advancements in hose and tubing materials and the integration

of sophisticated

tronics

including

controlled

elec-

microprocessor

robotic grade drives, have

led peristaltic become

pump

technology

the fastest growing

positive displacement metering

(PD) chemical

and sludge pump.

last decade, peristaltic

tens

to

type of In the

of thousands

of

pumps have been installed

in environmental

pumping

appli-

cations.

peristaltic

pumps

Integrating

Figure 1. A photograph of a typical municipal wastewater facility..

hose type peristaltic

highly abrasive and chemically ressive fluids demanded

agg-

by environ-

pump that does

not incur slip. As such, a hose pump is a 100% volumetrically

mental processes.

technology

efficient pump

where flow is independent

Supervisory

Unlike other PD pump technologies,

of pressure. All peristaltic

Control

Acquisition

which have tight tolerances

or inter-

inherently

ference

rotating

no packing

and

(SCADA)

Data

systems and plant PLCs is wires to pump

fits of the

parts, peristaltic tremely corrosive ferric chloride,

Today’s heavy-duty

peristaltic

pumps

are designed to operate 24171365 and combine precise PD flow and low maintenance

requirements

ability to handle

with the

extremely

abrasive

and aggressive fluids, which wear out more traditional

quickly

PD pump

technologies.

and abrasive

wetted

pumps keep exchemicals such as sodium hypochlorite

fluids such as various

sludges, lime and powdered activated carbon (PAC) slurries from wearing the pumps rotating fact, a properly pump

hose

components.

selected

does

not

In

heavy-duty fail due

to

in applying

peristaltic

technology

to environmental

seen in a

cations was the development element continuous

which duty

problem

HOSE

and required

2003

is no

chemicals emissions

potential

for

as

sludge

as

the

possibility

of

leaking from a seal box is

eliminated. Most peristaltic

pumps found in the

environmental

marketplace

incor-

porate two rollers or shoes that occabrasive grit in a grit removal system,

the

thickened

sludge,

moment,

nonabrasive

polymer, the hose life is

flow

perspective,

leakage. It is also an important safety feature when pumping dangerous

Regardless

rates, along with the ability to handle

January

there

pump

of a hose

is

seal that

comes in contact with the pumped fluid. This is especially convenient

appli-

could accommodate

or mechanical

abrasive wear; it only fails due to the total number of occlusions

In the past, the fundamental

pumps are

seal-less pumps. There

from a housekeeping

specific application.

PUMPS

positive displacement

sludge in a

with now commonplace

as simple as connecting terminal strips.

-20- “A WORLD

pump pumping

of product,

whether

lime

slurry

it is or

lude the hose. Twice per revolution pump’s rotor, both

of

for a very brief the

rollers/shoes

squeeze the tube/hose at the 6 and 12

the same. This is mainly due to the

o’clock position. At all times, at least

hose

one roller/shoe

pump

design

being

0262 1762/03/$

a truly

see front matter

is completely

occlu-

0 2003 Elsevler Science Ltd. All nghts reserved

ding the tube/hose. When the pump is

horsepower

turned off, the tube/hose is completely

motors

occluded

and

becomes

the

pump

tubing

pump designs

valve.

power

than

air in the

line

can

pass

through the occluded tube/hose. All peristaltic to

run

pumps have the ability

dry without

damage.

and causing catastrophic itself.

This

This

failure to the

is especially

true

when pumping liquids that contain such

as in dissolved

sludge

(DAF)

air

air floatation

or when

phragm

pumps

servo

peristaltic

use much

comparably

larger external

prevents the pump from vapor locking pump

grade

in many

a true in line check

Not even

as such,

robotic

utilized

that

less

sized

require

diamuch

are

two

environmental taltic

basic

groupings

applications

of

for peris-

and sludge feed/transfer.

a chemical of chemical

cations

found in a water and waste-

better

self

which

based on pumping

priming

water

pump,

well

water, can

The

treatment

metering

Chloride,

include

and

various

2) Sludge: Depending

a deep sump, a peristaltic pump will out

treatment

perform other PD pump technologies.

varying

Most peristaltic

Hose

pump designs are also

allowing

flushing

The

remains 100% volumetrically

pump efficient

in either direction. Peristaltic flow, viscous

provide

is ideal

polymers

undesirable. peristaltic

a gentle

for

where

Unlike

pumping

shearing

is

other PD pumps,

pumps are contamination-

free. Since

the liquid

contained

types

pumps

is completely

within the tube/hose, there

is no contamination

of the pump or

pumped fluid.

there

can

be and

including,

waste

sludge

In the

past,

choice

for

the

the

accepted

chemical

mechanically,

solenoid

(throw

pump. Unlike

however, internal

problem

when

check

capability as

as

275OO:l.

diaphragm

This

is

Another

common

diaphragm

problem

tube with the pump running

hypochlorite

applications.

hypochlorite

naturally

smallest

then

diameter

ting at minimum like

having

pumps than

switching

the

opera-

speed. It is literally

seven

in one

at full to

tube while

small

different unit

sized

no larger

the size of a breadbox.

Tubing

time

entrained

and

air

as in

of the tube is

located

pump

within

the

head

allowing for new ‘pinch points’ to be occluded tenance

by the cost

addition,

roller.

peristaltic

able to run dry without rotating

This

is virtually

main-

negligible. pumps

are

damage. The

parts of a peristaltic separated

pump

from

the

pumped fluid as the fluid only comes in contact

with the inside of the hose.

Sodium

erodes

subsequently

emits

‘off gas’. This gas or pocket the line -

will

known

often

to

sodium over an

of air in

cause

a diaphragm the this

and do not

occurs,

fractional

is still

running.

an operator

Figure 2. These photos show a problem diaphragm pump and replacement hose pump pumping sodium hypochlorite at a large wastewater treatment plant near Boston.

as vapor locking

pump

www.worldpumps.com

such that a new section

with

pumps are virtually silent in operation The

simply

one foot or so

to

pump to lose prime even though

vibrate.

employed

pumps

pumps is the inability

pump

and

is currently

needs to be adjusted

is a common

achieved by using the largest diameter speed

entire

down

of a single tubing pump can

much

the

pumps valves

carbon slurry.

be

to replace

The same piece of tubing

diaphragm

any aspect of the head/roller assembly turn

or

pumps, it is

or

meter solid laden fluids such as lime or

the

when a

maintenance

diaphragm

necessary

pumphead. that

expensive

of

the same pump head without resetting means

not

wearing

away)

peristaltic

clog or wear out. This

This

product

was

hydraulically

actuated

no

pump

metering

of the by the

to metal contacting

pump needs

are completely

Advantages vs other PD pump technologies

the ability

itself.

If the actual

By comparison,

repair, unlike

In

activated

return activated

have

to be used with

Ferric

Peristaltic

applications

A major advantage of tubing pumps is of tubing

Sodium

and grit removal.

diaphragm

for up to seven different

are

polymers.

of sludge.

sludge,

sludge (WAS),

pumps,

diameters

the many metal

tubing

are used for feed

of

thickened (RAS),

pumps

which

diaphragm

pumpage and could easily be corroded due to an abrasive

appli-

on the level of

in a plant,

transfer

for instantaneous

of lines.

a

pump would be contaminated

proposition.

pumps.

Sodium Bisulfite,

a 55-gallon drum, or lifting sludge from

back

when

fails, the internals

are a

that

peristaltic

most common

pumping chemicals

There

facilities

for

Hypochlorite,

through the top of

metering:

suited

achieve up to a 31’ suction lift. When

reversible,

as they

pump the hypo.

parts. This is an extremely myriad

no

with

pumps as they pump the

pump head is required.

hypochlorite. is

the

necessary

of air as efficiently

diaphragm

1) Chemical

There

pocket

Additionally,

emits an off gas such as with sodium

pump design than a peristaltic

peristaltic

and re-prime

is not

pump is repaired, often an entire new

tubing and hose pumps: chemi-

cal metering

the line

This

motors.

Environmental applications There

air from pump.

When

must bleed

the

WORLD

PUMPS

January 2003

21

Elimination equipment

of ancillary

A major

advantage

reduction

of ancillary

sludge

pumping

maintenance

of peristaltic

pump

equipment

required

system.

pump system.

is not

function

of the

suction

diameter.

major

pumps

reason

in

sludge

extremely

abrasive

Additionally,

for difficult grit

sludge

much

higher

required roughly

acceptance

is their

ability

Approximately

as pump have

to

speed

become

pump

damage. wear For the popular

and are now even used with

pump

the

screw. This

concentrations

increases.

increasingly

grit

allows of grit

directly

the pump while

to

the

to meter

reducing

flow to the screw from approximately

dampeners

flowmeters

are

pump

is

itself. Occasionally,

the use of inexpensive

and

to

pulsation

of the pump,

rather

pipe

1% of tubing

pump

installations

incorporate

dampeners.

installations

effectively

remove

length

a

discharge

and

98% of trace pulsation.

of hose to

do not wear due to abrasion;

applications

systems

dewatering

increasing

even grit itself, without

is linear

hose pumps

removal

system’s

sludge,

hose pumps

on a hose pump last decade,

for the

applications

pumps,

of the peristaltic

a function

and 35% of hose pump These

One

with tubing

require

This

and

must be added

to that of the flowmeter

pumps

dampeners.

or

installation

a true LCC for the entire

as the accuracy

superior

peristaltic

Figure 3. These are photographs of typical installations for diaphragm and peristaltic tubing pumps. It is clear which pump technology is more expensive purely from an installation perspective. Notice the many ancillary pieces of equipment required for diaphragm pumps that are not required for peristaltic pumps.

In addition,

eliminated,

usually

capital,

to provide

is the

in a chemical

costs of this extra equipment

that of the pump/motor

often

The

technology

the

240GPM

50GPM.

to

New developments Hose pumps Improvements bearing

in

design

the next

generation

the total

number

user

with

replacement

PERISTALTIC PUMP ROTH0 SYSTEM

for

PRESSURE UP TO lo/15 BAR, SUCTICN (BAR G) 0,98 SAFETY PROBE TO DETECT A WORN OUT TUBE

in tubing

water

small

line.

in leak detection the chemical

Further

improvements trim

of a remote

input

eliminate

By achieving and

hose

the lowest

embraced There

while

the technology ofthousands

and

into allows

failure,

while

a sealed head. the user to

operating

peristaltic

technology The

owners

themselves

short

of peristaltic

boxes.

tubing of ‘first

marketplace.

in a fairly

off

in output

signal control

Cost,

a

design

enhancements

a I’D pump

environmental community

are tens

throughout

inside

to

is a perfect

also allow

speed

Life Cycle

are now

head

a rare tubing

Further,

pressures

This

of chemical

pump

the need for separate

pumps

resort’ in the engineering

signal.

in size by almost

are allowing

in electronics pump

the footprint

for such high flow.

safely contained

the

the Hose

In addition,

while

amounts

upon

providing

or faster.

service.

Improved

led to reduce

reliability.

reduced

materials

keeping

signals

have

continuous

for built

manually

TFWJSFEFI FEEDING, METERING, FlLfRATlON OF: fra@e or sensitivefluids,

easier

coupled) have

pumps

while

to 350GPM

hose pumps

injecting

pressurized

These

and

is truly a small footprint

100 psi with

match

FLOW RATE FROM 26 LT/H TO 60.000 LT/H ON EIGHT MODEL6

been

closed designs

by one third

increased

Advancements reach

pumps.

performance

has never

of dual headed

(not

duty casing

of hose

better

have

half. This

coupled

of parts

even

capacities

direct

and heavier

consulting have

period

of time.

pumps

installed

??

the world.

CONTACT

Via Volta, 8 FAENZA ITALY Tel. ++39 546 620433 Fax ++39 546 621394 email: [email protected] website: www.ragazzini.it RES No.409

22

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- USE THE

January

2003

ENQUIRY

SERVICE

Rick Balek has held sales management positions with various pump manufacturers in the environmental marketplace for over 17 years and is currently National Sales Manager with Watson-Marlow Bredel Pumps and can be contacted at: Watson-Marlow Bredel Pumps Tel: +I-978-658-6168 Fax: +l-978-658-0041 rbalekOwmbpumps.com www.wmbpumps.com

@ www.worldpumps.com

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